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You asked:Intact macromolecular assemblies are analysed by advanced mass spectrometry. How large complexes (in molecular weight) have been studied
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[intact macromolecular assemblies]
  • To fully understand the workings of biological "nanomachines" it is necessary to obtain images of intact macromolecular assemblies in situ..[Daniel:2008]{Human}

[assemblies, been, complexes, intact/intact complex, macromolecular, mass/mass spectrometry, molecular weight]
  • In recent years mass spectrometry based techniques have emerged as structural biology tools for the characterization of macromolecular, noncovalent assemblies. Many of these efforts involve preservation of intact protein complexes within the mass spectrometer, providing molecular weight measurements that allow the determination of subunit stoichiometry and real-time monitoring of protein interactions. Attempts have been made to further elucidate subunit architecture through the dissociation of subunits from the intact complex by colliding it into inert gas atoms such as argon or xenon..[Richard:2009]{Human}

[assemblies, large complexes, macromolecular complexes, mass/mass spectrometry, mass/molecular mass]
  • Understanding the function of macromolecular complexes is related to a precise knowledge of their structure. These large complexes are often fragile high molecular mass noncovalent multimeric proteins. Classical biochemical methods for determination of their native mass and subunit composition were used to resolve their quaternary structure, sometimes leading to different models. Recently, the development of mass spectrometry and multi-angle laser light scattering (MALLS) has enabled absolute determination of native masses and subunit masses. Electrospray ionization mass spectrometry (ESI-MS) was used in denaturing and native conditions to probe subunit composition and noncovalent assemblies masses up to 2.25 MDa. In a complementary way, MALLS provides mass and size estimation in various aqueous solvents..[Matthieu:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[assemblies, been, complexes/complexes studied, large/large complexes, mass, molecular, spectrometry]
  • Bacteriophages belonging to the Caudovirales order possess a tail acting as a molecular machine used during infection to recognize the host and ensure high-efficiency genome delivery to the cell cytoplasm. They bear a large and sophisticated multiprotein organelle at their distal tail end, either a baseplate or a tail-tip, which is the control center for infectivity. We report here insights into the baseplate assembly pathways of two lactoccocal phages (p2 and TP901-1) using electrospray ionization-mass spectrometry. Based on our "block cloning" strategy we have expressed large complexes of their baseplates as well as several significant structural subcomplexes. Previous biophysical characterization using size-exclusion chromatography coupled with on-line light scattering and refractometry demonstrated that the overproduced recombinant proteins interact with each other to form large (up to 1.9 MDa) and stable assemblies. The structures of several of these complexes have been determined by x-ray diffraction or by electron microscopy. In this contribution, we demonstrate that electrospray ionization-mass spectrometry yields accurate mass measurements for the different baseplate complexes studied from which their stoichiometries can be discerned, and that the subspecies observed in the spectra provide valuable information on the assembly mechanisms of these large organelles..[Dale:2011]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[assemblies, macromolecular, molecular weights]
  • Herein we describe the impact of polymeric solutes on the thermal denaturation behavior of Au nanoparticle bioconjugate assemblies. Polymeric solutes can dramatically impact biochemical reactions via macromolecular crowding. Poly(ethylene glycol)s (PEGs) and dextrans of varying molecular weights were used as crowding reagents..[Glenn:2004]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry, molecular mass, weight]
  • Its primary structure was determined by a profitable combination of advanced mass spectrometry and automated sequence analysis of peptides obtained after cleavage of the purified protein. The enzyme subunit is composed of 210 amino acid residues accounting for a relative molecular mass of 24,112. It does not contain cysteine residues and has a high average of both hydrophobicity and amino acid weight..[Dello:1998]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[analysed, large, macromolecular, molecular weight, studied]
  • In the case of histone F2a2 (H2A) at pH 3.0 and ionic strength 0.1, the apparent weight-average molecular weight was determined at a number of macromolecular concentrations at five different temperatures. The self-association was analysed according to the method of Adams (published by Beckman Instruments Inc. in 1967) and shown to be a monomer-dimer-tetramer equilibrium. The association constants were evaluated at each of the temperatures studied and from their variation with temperature the values of the enthalpy and entropy of association were calculated. The intermolecular association was characterised by only a small change in enthalpy but a large, positive, change in entropy..[Diggle:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[assemblies, been, complex/complexes/large complexes, mass spectrometry, molecular]
  • Multi-subunit protein complexes are involved in many essential biochemical processes including signal transduction, protein synthesis, RNA synthesis, DNA replication and protein degradation. An accurate description of the relative structural arrangement of the constituent subunits in such complexes is crucial for an understanding of the molecular mechanism of the complex as a whole. Many complexes, however, lie in the mega-Dalton range, and are not amenable to X-ray crystallographic or nuclear magnetic resonance analysis. Techniques that are suited to structural studies of such large complexes, such as cryo-electron microscopy, do not provide the resolution required for a mechanistic insight. Mass spectrometry (MS) has increasingly been applied to identify the residues that are involved in chemical cross-links in compound protein assemblies, and have provided valuable insight into the molecular arrangement, orientation and contact surfaces of subunits within such large complexes..[Shannon:2011]

[assemblies, been, complex, molecular weights, weight]
  • This review summarizes developments and applications of flow and thermal field-flow fractionation (FFF) in the areas of macromolecules and supramolecular assemblies. In the past 10 years, the use of these FFF techniques has extended beyond determining diffusion coefficients, hydrodynamic diameters, and molecular weights of standards. Complex samples as diverse as polysaccharides, prion particles, and block copolymers have been characterized and processes such as aggregation, stability, and infectivity have been monitored. The open channel design used in FFF makes it a gentle separation technique for high- and ultrahigh-molecular weight macromolecules, aggregates, and self-assembled complexes..[Kim:2006]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry, mass spectrometry]
  • Recent developments in combined separations with mass spectrometry for sensitive and high-throughput proteomic analyses are reviewed herein. These developments primarily involve high-efficiency (separation peak capacities of approximately 10(3)) nanoscale liquid chromatography (flow rates extending down to approximately 20 nl/min at optimal liquid mobile-phase separation linear velocities through narrow packed capillaries) in combination with advanced mass spectrometry and in particular, high-sensitivity and high-resolution Fourier transform ion cyclotron resonance mass spectrometry..[Yufeng:2005]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Additionally, we introduce a range of analytical techniques involving high-performance liquid chromatography and mass spectrometry to detect and quantify retinoids and their derivatives in eye extracts. Biochemical protocols combined with advanced mass spectrometry should facilitate fundamental biological studies of vision..[Marcin:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, great, mass spectrometry, molecular weights]
  • In these instances, FD mass spectrometry has proven to be quite helpful. Molecular weights are obtained in a short time, eliminating the need for more time-consuming derivatization or chemical degradation methods. FD has been applied to the study of drug metabolism and has shown great promise in determining polar metabolites, including direct analysis of glucuronide, sulfate, and amino acid conjugates. Some problems have been encountered in handling samples of biological origins..[Brent:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[a mass, complex/complexes, intact, intact complex, large, molecular/molecular weight/molecular weights]
  • The measured electrophoretic mobility diameters, or Millikan diameters, of 32 well-defined proteins were plotted against their molecular weights in the range 3.5 to 1920 kDa and exhibited an excellent squared correlation coefficient (r(2) = 0.999). This finding allowed the exact molecular weight determination of large (glyco)proteins and noncovalent biocomplexes by means of this new technique with a mass accuracy of +/-5.6% up to 2 MDa at the femtomole level. From the molecular masses of the weakly bound, large protein complexes thus obtained, the binding stoichiometry of the intact complex and the complex stability as a function of pH, for example, can be derived. Examples of specific protein complexes, such as the avidin or catalase homo-tetramer, are used to illustrate the potential of the technique for characterization of high-mass biospecific complexes. A discussion of current and future applications of charge-reduced nano ESI GEMMA, such as chemical reaction monitoring (reduction process of immunglobulin G) or size determination of an intact virus, a supramolecular complex, and monitoring of partial dissociation of a human rhinoviruses, is provided..[Bacher:2001]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced, been, large, molecular weights, studied]
  • Cytochrome c oxidase from the inner membrane of yeast mitochondria consists of seven nonidentical protein subunits, three being synthesized on mitochondrial ribosomes ( molecular weights 43 K, 34 K, and 24 K) and four being made on cytoplasmic ribosomes ( molecular weights 14 K, 12 K, 12 K, and 4.5 K). In the present study all four cytoplasmically synthesized subunits of the enzyme were isolated on a large scale using ion exchange chromatography and gel filtration. Their amino acid composition as well as their amino- and carbosy-terminal amino acid residues have been determined. Sequence determinations of subunits IV and VI are already in an advanced state. The sequence of subunit VI is characterized by a large amino-terminal stretch dominated by charged amino acid residues followed by a cluster of hydrophobic amino acids. The binding site of yeast cytochrome oxidase for cytochrome c was studied by chemical crosslinking experiments..[Birchmeier:1977]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complexes, intact/intact molecular weights, large, molecular weight]
  • Elucidating native structure-function relationships of proteins identified using PAGE has been impeded by limitations in the isolation of intact proteins from the gel. By hydrolyzing polyacrylamide gel band under mildly acidic conditions rather than digesting entrapped proteins approximately 70% of a large native protein, mouse IgG1 ( molecular weight 150 kDa), was isolated. Further analysis indicated that the isolated antibodies had preserved specific binding capability to target antigens as well as intact molecular weights. This new technology may contribute to functional proteomic studies through the isolation of proteins in their native state after PAGE, and other technologies requiring simultaneous separation and isolation of other macromolecules and complexes..[Yoon:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been studied, macromolecular, molecular weights]
  • The self-association of the separate histone fractions isolated from chicken erythrocytes has been studied in solution at a number of different pH values and ionic strengths. The apparent molecular weights of the histones were determined over a range of macromolecular concentrations using the techniques of osmotic pressure and sedimentation equilibrium..[Diggle:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex/complexes, macromolecular, molecular weights, studied]
  • The purpose of this study is to investigate how the structures of polydisulfide Gd(III) complexes affect their pharmacokinetics and in vivo contrast enhancement as biodegradable macromolecular MRI contrast agents. A negatively charged polydisulfide Gd(III) complex, (Gd-DTPA)-cystine copolymers (GDCP), and a neutral agent, (Gd-DTPA)-cystine diethyl ester copolymers (GDCEP), with different molecular weights were prepared and characterized. The MRI contrast enhancement of the agents was studied in mice..[Yuda:2006]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, intact, mass spectrometry, molecular weight/molecular weights]
  • To fully characterize the 20S proteasome subunit composition and understand the subunit functions, we, the authors of this chapter, have developed and employed various mass spectrometry (MS)-based approaches to generate a comprehensive profile of the 20S proteasomes from rat liver and Tropanosoma brucei. We have identified 7 alpha and 10 beta subunits, including 7 essential and 3 nonessential beta subunits from rat 20S proteasome complex using two-dimensional (2-D) gel electrophoresis and tandem MS (MS/MS). In addition, multiple isoforms of most of the subunits were determined; indicating the composition of rat 20S proteasome complex was much more complicated than expected. Further analysis of the intact protein molecular weight of each subunit using LC-MS confirmed the heterogeneous population of the 20S proteasome and revealed that many of the experimental measured molecular weights do not correspond well with the theoretical values deduced from the sequences in protein databases..[Lan:2006]{Human}

[been, complexes, intact, molecular weights]
  • Crosslinked fibrin was digested by plasmin, and three soluble complexes larger than DD/E were purified and characterized. After gel filtration chromatography, the purified complexes were shown to have molecular weights of 465,000, 703,000, and 850,000, as determined by equilibrium sedimentation. Each of the complexes was dissociated into two or more fragments by SDS-polyacrylamide gel electrophoresis. The structure of these subunit fragments was deduced from determinations of their molecular weights and polypeptide chain composition and from known sites of plasmin cleavage of fibrin. Fragments larger than DD have been identified that contain intact gammagamma crosslinks as well as fragments resulting from cleavages at or near this site..[Francis:1981]{Human}

[been, complex, mass spectrometry, molecular weight]
  • Molecular weight distributions (MWDs) of model polyaromatic hydrocarbons (PAHs) and complex asphaltene samples have been investigated in laser desorption/ionization mass spectrometry (LDI-MS) experiments..[Bruno:2007]
  • Electrospray ionization (ESI) was combined with ultra-high-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FTICR MS) to characterize complex humic and fulvic acid mixtures. Lower than expected molecular weight distributions previously observed for humics when analyzed by ESI-MS have fueled speculation about a bias in favor of low molecular weight. Multiply charged ions, ionization suppression, and sample fragmentation have all been suggested as sources of this low molecular weight bias..[Alexandra:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • For this, the "top down" mass spectrometry (MS) approach, extended by the greatly increased protein fragmentation from electron capture dissociation (ECD), has been applied to characterize proteins involved in the biosynthesis of thiamin, Coenzyme A, and the hydroxylation of proline residues in proteins. With Fourier transform (FT) MS, electrospray ionization (ESI) of a complex mixture from an E. coli cell extract gave 102 accurate molecular weight values (2-30 kDa), but none corresponding to the predicted masses of the four desired enzymes for thiamin biosynthesis (GoxB, ThiS, ThiG, and ThiF). MS/MS of one ion species (representing approximately 1% of the mixture) identified it with the DNA-predicted sequence of ThiS, although the predicted and measured molecular weights were different..[Ying:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, macromolecular, molecular weight, weight]
  • Polymer molecular weight was less important than polymer chemistry and weight percent in solution. For a high (15%) weight percent of PEG, aggregation was observed even in the absence of complementary oligonucleotides. These results underscore the importance of polymer chemistry in addition to physical volume exclusion in macromolecular crowding and point to the importance of understanding these effects when designing biorecognition-based nanoparticle assembly schemes in complex matrixes (i.e., any involving polymeric solutes)..[Glenn:2004]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[large, mass spectrometry, molecular weight]
  • Mass spectrometry has revealed microheterogeneity among the proteins belonging to each of these two groups, suggesting a total number of OBPs of at least nine. The molecular weight differences between OBPs cannot be readily accounted for by common post-translation modifications and indicate different gene products. Such a large number of different OBPs may represent further support to an odour discriminating role for these proteins..[Ganni:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex macromolecular assemblies]
  • Cryofixation by high pressure freezing circumvents many of the artifacts since it allows vitrifying biological samples of about 200 mum in thickness and immobilizes complex macromolecular assemblies in their native state in situ..[Daniel:2008]{Human}

[been analysed, mass spectrometry, molecular weight/molecular weights]
  • Mixtures of a specific group of proteins, the major urinary proteins (MUPs), believed to have a role in odorant binding, have been analysed by electrospray ionization mass spectrometry. The data obtained from conventional transformed electrospray data confirm that the molecular weights of the protein mixtures, deduced from published sequences, lie in the molecular weight range 18,600 to 19,000 Da..[Evershed:1993]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry, been, molecular]
  • Despite many early disappointments and the resulting skepticism, real progress has been made with exciting new prospects for cancer research. This review summarizes currently available proteomic tools for identifying novel biomarkers and drug targets, as well as an overview of their application in research on molecular mechanisms of carcinogenesis. Emphasis is given to novel sample preparation methods, protein separation and identification techniques, and advanced mass spectrometry tools for quantitative proteomic..[Georgia:2009]{Human}

[been, intact, mass/mass spectrometry, molecular weights]
  • A combination of mass spectrometric techniques (electrospray mass spectrometry, liquid secondary-ion mass spectrometry (LSIMS), tandem mass spectrometry) has been used for variant hemoglobin detection and characterization. Electrospray mass spectrometry allowed analysis of mixtures of intact globins giving the molecular weights (accuracy 1-2 Da), and information about relative amounts of globins present, simultaneously..[Falick:1992]{Human}

[macromolecular, molecular weights, studied]
  • As part of the strategy for the design of macromolecular carriers for drug targeting, the disposition characteristics of macromolecules were studied in mice bearing tumors that served as target tissues. Eight kinds of macromolecules including four polysaccharides and four proteins with different molecular weights and electric charges were used; tissue distribution and tumor localization after intravenous injection were studied..[Takakura:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complexes, macromolecular, molecular weight]
  • The increase in the molecular weight of GDCP resulted in prolonged in vivo contrast enhancement in the blood pool. The structural modification of polydisulfide Gd(III) complexes resulted in biodegradable macromolecular MRI contrast agents with different degradability and in vivo contrast enhancement..[Yuda:2006]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[mass spectrometry, molecular weights]
  • In many cases, the manufacturers' listed molecular weights and polydispersity measurements for biodegradable polymers are determined by size-exclusion chromatography and the data obtained by that method may differ considerably from the high-precision matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results presented here..[Alain:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • A computer program is described that can rapidly process low-resolution electrospray liquid chromatography/ mass spectrometry (LC/MS) for peptides and proteins and assign molecular weights for observed components..[Pearcy:2001]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • This optimized method provided a separation of antibody light chain and heavy chain based on size and allowed a direct measurement of molecular weights by mass spectrometry..[Hongcheng:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[large, macromolecular complex, molecular weight/molecular weights]
  • Analysis of the labeled glycocalyx by agarose gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), as well as enzymatic and pH-dependent hydrolysis indicated that the glycocalyx is a trichloro-acetic acid-soluble macromolecular complex of high molecular weight composed of a peptide moiety attached to large prosthetic groups (presumably carbohydrates) by O-glycosidic bonds. Analysis of the labeled apical plasma membrane components by agarose gel filtration and SDS-PAGE disclosed the presence of six major species of apparent molecular weights: 23,000, 28,000, 37,000, 44,000, 68,000, and 95,000. More than half of the membrane-associated radio-iodine was in two bands of molecular weights 37,000 and 44,000..[Rodriguez:1979]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been studied, complexes, mass spectrometry]
  • Supramolecular complexes consisting of a single-stranded oligothymine (dTn) as the host template and an array of guest molecules equipped with a complementary diaminotriazine hydrogen-bonding unit have been studied with electrospray-ionization mass spectrometry (ESI-MS)..[Pim:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complexes, molecular weights, studied]
  • The methodology has been applied to the 20S core particle to reveal functionally important motions and interactions by recording spectra on complexes with molecular weights of up to a megadalton. Our results establish that NMR spectroscopy can provide detailed insight into supra-molecular structures over an order of magnitude larger than those routinely studied using methodology that is generally applicable..[Remco:2007]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, mass spectrometry, molecular/molecular weights, weight]
  • Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry (MS) has emerged as a powerful, sensitive technique for structural analysis of glycosaminoglycans (GAGs) and their fractions and fragments. Whereas the molecular size of low sulfated or nonsulfated species (such as low-molecular weight [LMW] K5 polysaccharides) can be directly determined up to molecular weights (MWs) of 12 kD, polysulfated species require complexing with a basic polypeptide and at present can be characterized (in terms of both MW and end residues) up to the size of a decasaccharide, even in complex mixtures. MALDI spectra of GAG oligosaccharides in the presence of a complexing protein permit to assess binding to the protein and the presence of multimeric complexes..[Sturiale:2001]{Human}

[been, mass/mass spectrometry, molecular mass, molecular weight]
  • An analytical approach has been described for the molecular weight characterization of enzymatically degraded hyaluronic acid (HA). The approach involved the combined use of aqueous gel filtration chromatography (GFC) with matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). Microfractions were collected across an eluting peak from the chromatography system, followed by mass spectrometric analysis of these narrow fractions. The molecular mass determined by MALDI-MS and the signal obtained from the chromatography established a calibration curve for other hyaluronic acid samples analyzed by this GFC system..[Yeung:1999]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[assemblies, complex mass, complex/complexes]
  • We were able to detect single-stranded-DNA (ssDNA)-guest complexes for strands with lengths of up to 20 bases, in which the highest complex mass detected was 15 kDa; these complexes constitute 20-component self-assembled objects. Gas-phase breakdown experiments on single- and multiple-guest-DNA assemblies gave qualitative information on the fragmentation pathways and the relative complex stabilities..[Pim:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, large, a mass/mass/mass spectrometry, molecular mass, molecular weight/molecular weights]
  • Glycosylated human plasminogen activator inhibitor type 1 (PAI-1), produced in Chinese hamster ovary (CHO) cells, showed a variety of compounds with different molecular weights when subjected to electrospray mass spectrometry (ES-MS), owing to the heterogeneity of the carbohydrate chains. However, non-glycosylated human PAI-1, produced in E. coli, gave rise to a prominent species with a molecular weight of 42,774, consistent with the amino-acid sequence. A non-glycosylated mutant of the proteinase domain (B-chain) of tissue-type plasminogen activator (tPA) produced in C 127 cells, had a molecular weight of 28,168. Full-length, glycosylated, tPA showed a large heterogeneity in molecular mass. For a mass study, a tPA-PAI-1 complex was formed, composed of non-glycosylated PAI-1 and non-glycosylated B-chain. This complex was remarkably stable at room temperature in buffer with a neutral pH. The mass spectrum of the complex provided two main species, a peptide with a mass of 3803 and a dominating species of 67,133. These masses are consistent with a complex where PAI-1 is cleaved at the P1-P1' position. A trace of a species with a molecular mass of 70,942 was also found, corresponding to the complete, non-dissociated complex with PAI-1. Separation of the cleaved peptide, corresponding to the hydrophobic C-terminal 33 amino-acid residues of PAI-1, from the complex, was achieved by size-exclusion chromatography in the presence of 30% acetonitrile. Thus, in the complex between tPA and PAI-1, the proteins are held together by a tight covalent bond, but the C-terminal cleaved peptide of PAI-1 is only bound to the complex by hydrophobic forces. To assess whether this is specific to the tPA B-chain alone, experiments with the complex of full-length, glycosylated tPA and glycosylated PAI-1 were also performed, and it was possible to demonstrate the release of the C-terminal PAI-1 peptide by chromatography, mass spectrometry, as well as by SDS-PAGE..[Str?mqvist:1996]{Human}

[intact, mass/mass spectrometry/molecular mass, molecular weights]
  • Matrix-assisted laser desorption with concomitant ionization, in combination with a linear time-of-flight mass spectrometer, was used to analyze underivatized and hard-to-solubilize surface layer proteins and glycoproteins by depositing them on top of a microcrystalline layer of the matrix alpha-cyano-4-hydroxycinnamic acid. Use of this special sample preparation technique allowed the first successful desorption-ionization of intact surface layer proteins and accurate determination of their molecular weights by mass spectrometry. The molecular mass of the monomeric subunit of the major surface layer protein isolated from Clostridium thermosaccharolyticum E207-71 was determined to be 75,621 +/- 81 Da. The obtainable mass accuracy of the technique is conservatively considered to be within +/- 0.2%..[Allmaier:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[intact molecular, large, mass/mass spectrometry, molecular weight/molecular weights]
  • Because of the high molecular weights and thermal lability of biomolecules such as nucleic acids and protein, they can be difficult to analyze by mass spectrometry. Such analyses require a "soft" ionization method that is capable of generating intact molecular ions. In addition, most mass analyzers have a limited upper mass range that is not sufficient for studying these large molecules. ESI-MS can be used to analyze molecules with a molecular weight that is larger than the mass-to-charge ratio limit of the analyzer..[Colette:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry, been]
  • It has been proposed that if protein tyrosine kinases (PTKs), protein tyrosine phosphatases (PTPs), and thousands of their substrates could be identified and characterized, it would significantly advance our understanding of the underlying mechanisms that control animal development and physiological homeostasis. The fruit fly Drosophila melanogester has been used extensively as a model organism for investigating the developmental processes, but the state of its tyrosine phosphorylation is poorly characterized. In the current study, we used advanced mass spectrometry (MS)-based shotgun analyses to profile the tyrosine phosphoproteome of Drosophila S2 cells..[Ying-Che:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Full structural definition and glycosylation site mapping were completed through advanced mass spectrometry analyses at both the glycan and glycopeptide levels in conjunction with chemical and enzymatic cleavages. Although similar occurrence of such terminal disialyl cap on the N-glycans of several mammalian glycoproteins has been implicated, most of these correspond to only minor constituents of the full glycomic heterogeneity and remain poorly characterized..[Chia-Wei:2011]{Human}

[advanced mass spectrometry, complex]
  • Advanced mass spectrometry methods can unambiguously identify more than 2,000 proteins in a single proteome. Complex mixture analysis is not limited by sensitivity but by a combination of dynamic range (high abundance peptides preventing sequencing of low abundance ones) and by effective sequencing speed..[Lyris:2006]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, mass spectrometry, molecular weight/molecular weights]
  • The molecular weight profiles of low molecular weight heparin samples have been measured by high-performance gel permeation chromatography using as calibrant the heparinase-degraded material (90/686) now established as the 1st International Reference Preparation (IRP) Low Molecular Weight Heparin for Molecular Weight Calibration Use of the calibrant as a broad molecular weight standard is described and a calibration table provided based on data collected over several years in one laboratory. In order to confirm the assignment of degree of polymerisation to resolved oligosaccharide peaks in the calibrant, molecular weights of oligosaccharides fractionated from the 1st IRP were independently determined by fast atom bombardment mass spectrometry (FAB MS). The molecular weight distributions of commercial low molecular weight heparins have been characterized. Measurements of molecular weight parameters of heparin molecular weight standards from several sources provide comparisons between the molecular weight scales of this and other studies..[Mulloy:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The molecular weight of peptides can be determined by fast-atom bombardment mass spectrometry (FAB-MS) following polyacrylamide gel electrophoresis (PAGE). Initial results combining the fast and efficient separation of peptides by PAGE and the unambiguous determination of molecular weights by FAB-MS have been demonstrated for the three peptides bradykinin, neurotensin and gramicidin S. This method has also been applied to the determination of the molecular weights of two fragments from the tryptic digest of horse-heart cytochrome c..[Camilleri:1992]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The primary structure of Paim I has been determined by Edman degradation and fast atom bombardment mass spectrometry (FABMS). This protein is a single-chain polypeptide of 73 amino acid residues with a calculated molecular weight from the sequence data of 7415.3 (monoisotopic molecular weight) and 7420.2 (average molecular weight)..[Hirayama:1988]{Human}
  • From these results the subunit assembling of erinacin has been formulated as alpha(10).2beta(10). The molecular weight of the subunits and of the beta-subunit decamer was confirmed by MALDI-TOF mass spectrometry..[Omori-Satoh:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, mass spectrometry, molecular weight/molecular weights]
  • Nanoscale liquid chromatography coupled to electrospray ionization mass spectrometry was used to identify the nature of the ligand that binds noncovalently to siderocalin (lipocalin 2). The folded state siderocalin-ligand complex was separated from free, unfolded siderocalin using reversed phase chromatography, and the molecular weight of the siderocalin ligand was then determined from the deconvoluted molecular weights of the complex and of the free protein..[Catalin:2004]{Human}

[been, complexes, molecular weight/molecular weights, spectrometry]
  • Liquid chromatography-mass spectrometry (LC-MS) has been used extensively in determination of the molecular weights of proteins, as well as covalent protein-ligand complexes. We have successfully developed LC-MS method for protein molecular weight measurement using small-bore and capillary LC-MS under acidic and basic conditions. A high pH method was critical in studying complexes that were unstable under acidic conditions..[Stone:2005]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, a mass/mass spectrometry, molecular weights, studied]
  • Size-exclusion chromatography (SEC) has been widely used to detect antibody aggregates, monomer, and fragments. SEC coupled to mass spectrometry has been reported to measure the molecular weights of antibody; antibody conjugates, and antibody light chain and heavy chain. In this study, separation of antibody light chain and heavy chain by SEC and direct coupling to a mass spectrometer was further studied..[Hongcheng:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, mass, molecular weights]
  • A detailed study of the mass spectra of peptides produced by the new technique of fast-atom bombardment is reported. Molecular weights of unmodified peptides containing up to 21 amino acids have been determined..[Williams:1982]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complex, large complexes, molecular weight/molecular weights]
  • Fluorescence polarization has been used to study the interaction of thrombin and heparin, and the catalysis by heparin of the combination of thrombin and antithrombin. At low ionic strength (20 mM Tris, pH 7.4), the addition of heparins of known molecular weights to thrombin led to the formation of large complexes (defined as ' complex 1'). Further addition of heparin led to a rearrangement of these large complexes to form smaller complexes (defined as ' complex 2'). The molar ratio of thrombin to heparin in complex 1 increased with increasing heparin molecular weight, and corresponded to one thrombin molecule for every heparin segment of Mr 3000. The stoichiometry of complex 2 was 1 heparin to 1 thrombin, irrespective of the heparin molecular weight..[Evington:1986]{Human}

[intact, macromolecular, studied]
  • The barrier properties of lipopolysaccharide were studied by testing the influence of O-antigen on the binding of ligand to maltoporin in the outer membranes of Escherichia coli and Salmonella typhimurium. Maltoporin (LamB protein) of Escherichia coli K-12 was capable of interacting with macromolecular starch polysaccharides, as was previously shown by the binding of intact bacteria to fluorescein-labeled amylopectin or to starch-Sepharose columns..[Ferenci:1986]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry]
  • Combinations of affinity-enrichment techniques, chemical and biochemical protocols, and advanced mass spectrometry facilitate detailed glycoprotein analysis in proteomics, from fundamental biological studies to biomarker discovery in biomedicine..[David:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complex, mass, molecular weight]
  • Results for the entire run are then sorted by mass and those values found in adjacent scans are grouped together. The list of found components can also be compared to a user defined list of target molecular weight values making it easy to compare the results from different analyses. The program also has the capability to process a rolling average of scans that improves the performance when analyzing high molecular weight components. Other program features facilitate closer examination of selected spectra or regions of the chromatogram to check the MoWeD mass assignments. The utility of the program was demonstrated by the analysis of LC/MS data derived from a complex mixture of proteins derived from a bacterial whole cell lysate that had previously been analyzed manually..[Pearcy:2001]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[mass spectrometry, molecular weight/molecular weights]
  • The structures of polyaminoborane 8a and copolymers 8b and 8c were further analyzed by ultrahigh resolution electrospray mass spectrometry (ESI-MS), and 8a, together with insoluble homopolymer 8d, was also characterized by (11)B and (1)H solid-state NMR, IR, and wide-angle X-ray scattering (WAXS). The data indicate that 8a-8c are essentially linear, high molecular weight materials and that the insoluble polyaminoborane 8d possesses a similar structure but is of lower molecular weight (ca. 20 repeat units), presumably due to premature precipitation during its formation. The yield and molecular weight of polymer 8a was found to be relatively robust toward the influence of different temperatures, solvents, and adduct concentrations, while higher catalyst loadings led to higher molecular weight materials. It was therefore unexpected that the polymerization of 7 using 5 was found to be a chain-growth rather than a step-growth process, where high molecular weights were already attained at about 40% conversion of 7..[Anne:2010]
  • The application of nonpolar matrices for the analysis of low molecular weight nonpolar synthetic polymers using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is demonstrated. Anthracene, pyrene, and acenaphthene were utilized as nonpolar matrices for the analysis of polybutadiene, polyisoprene, and polystyrene samples of various average molecular weights ranging from about 700 to 5,000..[null:2000]

[analysed, been, mass/mass spectrometry, molecular weight/molecular weights]
  • For at least two decades different mass spectrometric techniques have been applied for polymer analysis, including the qualitative determination of chemical compositions, end group identification, functionality type distribution and the determination of the cyclisation extend at each degree of polymerisation. Molecular weights exceeding 100 KDa are provable by MALDI-ToF mass spectrometry. Further, molecular weight distributions are determined by MADLI-ToF. However, there are some hints that, there is a discrimination against higher molecular weight species in samples with polydispersity of more than 1.2. Furthermore, pathways for dendritic and hyper-branched polymers, supramolecular polymers and nano condensates are analysed by help of mass spectrometry..[Joachim:2005]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[analysed, mass spectrometry, molecular weight]
  • In immunoblotting, distinct reactions were noted for proteins of molecular weight ranges of 25-49 kDa, 61-95 kDa, and 108-214 kDa. Proteins of the molecular weight of 68, 75 and 86 kDa were analysed using mass spectrometry and matched with the highest probability to proteins in the NCBI data base..[Puchalski:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[analysed, mass/mass spectrometry, molecular weight]
  • The tryptic peptides were separated by C-18 reverse phase HPLC and analysed by LSIMS to narrow down the mutation site to a single peptide. In some instances, the molecular weight of a variant peptide was sufficient to determine the mutation uniquely. When molecular weight information alone was insufficient to identify the mutation and its site, the peptide was sequenced by tandem mass spectrometry on a 4-sector instrument. In cases where more than one possible mutation site was present in the peptide and the mutation resulted in a change of only 1 Da in the peptide mass, the resolution and mass measurement accuracy of the 4-sector machine were essential in determining the correct sequence..[Falick:1992]{Human}

[a mass, large complexes, molecular/molecular weight/molecular weights]
  • Studies in the presence of varying concentrations of Mg2+ showed that the method provided valid molecular weights for RNAs of differing amounts of ordered structure. The molecular weight (X 10(-6)) of the high molecular weight RNA complexe from Rous sarcoma virus was 7.6 (+/-0.3) and from murine leukemia virus was 6.9 (+/-0.3). The molecular weights (X 10 (-6) of their Subunits were 3.3 (+/-0.1) and 2.8 (+/-0.2), respectively. Hence, the large complexes consisted of two, not three or more, subunits plus small associated RNAs. The high molecular weight RNA from cloned Rous sarcoma virus was heterogenous in molecular weight although the apparent molecular radius was constant; stuides were performed on subfractions of the RNA as well as on RNA from virus harvested at various time intervals. The preparations with lowest molecular weight approached a mass equal to twice that of the subunit, with hydrodynamic properties approaching those expected of normal single-stranded RNA..[King:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, large, large molecular assemblies/molecular, molecular weight]
  • The machinery used by the cell to perform essential biological processes is made up of large molecular assemblies. One such complex, the proteasome, is the central molecular machine for removal of damaged and misfolded proteins from the cell. Here we show that for the 670-kilodalton 20S proteasome core particle it is possible to overcome the molecular weight limitations that have traditionally hampered quantitative nuclear magnetic resonance (NMR) spectroscopy studies of such large systems..[Remco:2007]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[macromolecular, molecular/molecular weights, studied]
  • The transport of dextrans (approximately 4 to approximately 150 kDa) across an in vitro model of the alveolar epithelial barrier was studied to determine the effects of molecular size on pulmonary absorption of macromolecular drugs. Fluorescein isothiocyanate (FITC)-labeled dextrans (FDs) with average molecular weights (all in kDa) of 3.86 (FD4), 9 (FD10), 19.8 (FD20), 40.5 (FD40), 71.6 (FD70), and 156.9 (FD150) were utilized as model macromolecular drugs..[Matsukawa:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, intact, molecular weight/molecular weights, studied]
  • Human amyloid A protein (AA) is usually composed of the NH2-terminal 76 amino acid residue of serum amyloid A protein (SAA), although lower and higher molecular weight fragments have been reported. We studied the primary structure of six AA proteins with molecular weights of 11 kDA-15kDA, as determined by SDS-PAGE. Automated Edman degradation of the intact purified proteins and sequence analysis of enzymatic peptides revealed that the AA proteins were composed of only 74 to 87 residues..[Prelli:1991]{Human}

[complex, intact, molecular weight/molecular weights, weight]
  • These qualities produce spectra that allow an accurate and sensitive determination of the number average molecular weights, weight average m.w., and polydispersity index of labile polar polymers. With such polymers, many solid matrices produce spectra showing extensive polymer degradation leading to the underestimation of molecular weights. The distribution of intact analyte peaks obtained with the ILM DEA-CHCA allows for identification of the fine structure of complex copolymers. ILMs were much less susceptible to effects of extraction delay times on molecular weight determination than were solid matrices..[Alain:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry/mass, complex, mass spectrometry]
  • It can also be used on its own in conjunction with tandem mass spectrometry (MS/MS) for the direct analysis of complex proteins. Here, we describe a strategy combining isolation of purified plasma membrane, efficient digestion of plasma membrane proteins in polyacrylamide gel, and high-sensitivity analysis by advanced mass spectrometry to create a new rapid and high-throughput method. The plasma membrane protein mixture is directly incorporated into a polyacrylamide gel matrix, After formation of the gel, proteins in the gel section are digested with trypsin, and the resulting peptides are subjected to reversed-phase, high-performance liquid chromatography followed by electrospray ion-trap tandem mass analysis..[Rui:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [advanced mass spectrometry, complex, mass spectrometry]
    • In a broader context of developing high sensitivity mass spectrometry methodologies for glycomic identification of Le(a) versus Le(x) and linear versus branched poly-N-acetyllactosamine (polyLacNAc), we have now shown that the dimeric type 1 glycan chain, as carried on the lactosylceramides of a human colonic adenocarcinoma cell line, Colo205, not only can be further extended linearly but can likewise be branched at C6 of 3-linked Gal in a manner similar to polyLacNAc. A combination of chemical and enzymatic derivatization coupled with advanced mass spectrometry analyses afforded unambiguous identification of a complex mixture of type 1 and 2 hybrids as well as those fucosylated variants founded exclusively on linear and branched trimeric type 1 chain..[Yao-Yun:2008]{Human}

[been, intact, molecular weight]
  • Three different analytical techniques (planar SDS-PAGE, CGE-on-a-chip and MALDI-TOF-MS) applied for determination of the molecular weight of intact and partly and completely de-N-glycosylated human serum glycoproteins (antithrombin III and coagulation factor IX) have been compared..[M?ller:2007]{Human}

[been, complex, large, mass/mass spectrometry, molecular weight/molecular weights]
  • A selection of hydroxyacetophenones has been investigated as matrices for the analysis, by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), of high molecular weight (HMW) glutenin mixtures from three wheat varieties. Mass spectra were obtained directly from the HMW glutenin extracts without any preliminary purification and separation steps. According to the quality of the mass spectra, obtained using different hydroxyacetophenones, it has been possible to classify the matrices on the basis of their suitability for the analyte properties. Only two of the matrices considered showed to be compatible with the HMW glutenin mixtures analysis, although a large amount of other highly complex protein mixtures are present. This study indicates that MALDI-MS, as a stand-alone technique, is particularly useful for the direct determination of the complete HMW subunits profile and their molecular weights..[null:1999]

[been, complex/complexes, great, molecular weight/molecular weights, studied]
  • These isoenzymes have been found to form complexes with other proteins; however, traditional isolation procedures involving ammonium sulphate precipitation and/or ion exchange chromatography do not allow for the isolation of these complexes. The present paper reports a fast and gentle procedure for the isolation of myrosinases in the complex form. Partial purification by Con A affinity chromatography followed by Sephadex G-200 gel filtration allowed for the isolation of myrosinase complexes from seeds of Brassica carinata, B. oleracea var. capitata, B. napus and Sinapis alba. Myrosinases in the Brassicas formed complexes of different molecular weight (500-600 kDa, 270-350 kDa and 140-200 kDa) whereas in seeds of S. alba it was only possible to isolate and detect 140-200 kDa complexes. In all species the complexes were formed by isoenzymes with isoelectric points between 4.8 and 5.6 and in some cases up to 6.8. SDS-PAGE confirmed that the myrosinase isoenzymes were composed by several protein subunits of molecular weights ranging between 10 and 110 kDa. The relative amount and enzymatic activity of the myrosinase complexes varied amongst the species studied. The isolation of myrosinase complexes in their native form is of great importance for the study of the hydrolysis of glucosinolates under autolysis conditions..[Natalia:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, intact, large, mass/mass spectrometry, molecular/molecular weight/molecular weights]
  • The extension of mass spectrometry to high molecular weight biopolymers based upon electrospray ionization and the on-line combination with capillary electrophoresis is described. Electrospray ionization produces gas-phase intact multiply charged molecular ions of biomolecules from highly charged liquid droplets by a high electric field. For high molecular weight substances electrospray ionization results in a characteristic bell-shaped distribution of multiply charged ions, with each adjacent major peak in the spectrum differing by one charge. Multiply charged molecular ions of proteins with molecular weights greater than 130,000 have been observed with a quadrupole mass spectrometer of limited mass-to-charge range (m/z 1700). Molecular weights can be readily determined for large proteins with accuracies in the range of +/- 0.01 to 0.05%; at least an order of magnitude further improvement appears feasible with improved techniques and instrumentation..[Loo:1989]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[mass spectrometry, molecular]
  • If the Protein-A bound autoantibodies recognized their antigens, these proteins could be separated by their molecular masses and were to be detected by mass spectrometry..[Franz:2003]{Human}

[mass, molecular, spectrometry]
  • With their absolute mass determination, the very high precision of spectrometry and the versatile nature of light scattering, ESI-MS and MALLS have provided a wealth of data helping to resolve parts of controversies for HBL-Hb models and opening access to new fields of investigation in structural diversity and molecular adaptation..[Matthieu:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[large, molecular weights]
  • The molecular weights of the large genomic RNAs from Rous sarcoma and Moloney murine leukemia viruses were determined by a combination of sedimentation coefficients and retardation coefficients from gel electrophoresis..[King:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Compounds with low molecular weights (approximately 10 kD) or positive charges showed lower tumor radioactivity accumulation; radioactivity was rapidly eliminated from the plasma via rapid urinary excretion or extensive hepatic uptake, respectively. On the other hand, large and negatively charged compounds, carboxymethyl dextran, bovine serum albumin, and mouse immunoglobulin G, showed higher radioactivity accumulation in the tumor (calculated total amounts were 15.6, 10.8, and 20.8% of the dose, respectively) and prolonged retention in the circulation..[Takakura:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, molecular mass, molecular weight/molecular weights]
  • In the present study, we have shown complex on-chip antibody-antigen reactions. At higher molecular weights (> 30 kDa) the detection sensitivity of this on-chip method was comparable to conventional Western blotting. At lower molecular mass, the Western blot technique is easily exceeded by the on-chip method. Considering that this on-chip procedure is quite easy to use, is much less time-consuming than Western blotting, and is much more sensitive at least in the low molecular weight range, the SELDI-TOF technology is a very promising approach for the screening of autoantibodies in autoimmune diseases. Due to its versatility, this on-chip technology could allow the large-scale screening for complex autoantibody distributions for diagnostic purposes and early detection of autoimmune diseases might be possible..[Franz:2003]{Human}

[analysed, complexes/large complexes, molecular weight/molecular weights]
  • As a first stage, DNA expression vectors (6 kb) were condensed with poly(L)lysine of different molecular weights (3970-224 500) to form polyelectrolyte complexes and analysed by atomic force microscopy (AFM). Discrete complexes were formed in every case, although the highest molecular weight poly(L)lysine preparation (224 500) produced large complexes with significant polydispersity (diameters ranging from 120-300 nm), while the smallest poly(L)lysine (3970) produced more homogeneous complexes with diameters ranging from 20-30 nm. Poly (L)lysine preparations of molecular weight 53 700 and 23 800 produced complexes of intermediate size and poly-dispersity. The mean volumes of the complexes formed using poly(L)lysine 224 500 and 3970 were 606 000 nm3 and 3700 nm3, respectively. Polyelectrolyte complexes formed using low molecular weight poly(L)lysine also showed significantly decreased cytotoxicity. Given restrictions of access to many cellular targets and the need for good biocompatibility, synthetic vectors based on DNA condensed with low molecular weight polycations may be more appropriately developed for general use..[Wolfert:1996]{Human}

[complex/complexes, large, molecular weight]
  • A schematic model was developed to explain the structure of the large noncovalently bound complexes based on their molecular weight and observed component fragments. Our scheme supports the two-stranded half-staggered overlap model as the basic unit of fibrin structure, in which each complex consists of fragments from two adjacent complementary antiparallel fibrin strands..[Francis:1981]{Human}

[been, intact, a mass/mass/mass spectrometry, molecular weight/molecular weights]
  • A liquid-phase three-dimensional protein separation method has been developed that is used to separate the cytosolic fraction of a HEL cell lysate via isoelectric focusing (IEF), nonporous silica (NPS) reversed-phase high-performance liquid chromatography (RP-HPLC) and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS), respectively. Several hundred unique protein molecular weights were observed in a pI range from 4.8 to 8.5 and a mass range from 5 to 85 kDa. Proteins were positively identified by analysis of the pI (+/-0.5 pI units), an intact protein molecular weight (+/-150 ppm), and peptide mass mapping results. Using the molecular weight (MW) and peptide mapping results of identified proteins it was possible to characterize their posttranslational (PTMs) and/or sequence modifications..[Wall:2001]{Human}

[been studied, mass, molecular weight/molecular weights]
  • In this study, the hydrolytic degradation of polyglyconate B has been studied in vitro. Specimens were prepared with two initial molecular weights and aged in PBS solution at 37 degrees C for up to 31 days. The polymers were characterised by gel permeation chromatography. for molecular weight, tensile testing and mass change, as a function of degradation time..[Farrar:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, large, mass/mass spectrometry, molecular weight/molecular weights]
  • Gas-phase ion/molecule chemistry has been combined with ion mobility separation and time-of-flight mass spectrometry to enable the characterization of large poly(ethylene glycol)s (PEGs) and PEGylated molecules (>40 kDa). A facile method is presented in which gas-phase superbases are reacted in the high-pressure source region of commercial TOF mass spectrometers to manipulate the charge states of large ions generated by electrospray ionization (ESI). Charge stripping decreases the spectral congestion typically observed in ESI mass spectra of high molecular weight polydisperse PEGylated molecules. From these data, accurate average molecular weights and molecular weight distributions for synthetic polymers and PEGylated proteins are determined. The average MW measured for PEGylated Granulocyte colony-stimulating factor (rh-GCSF, 40 726.2 Da) is in good agreement with the theoretical value, and a 16 Da mass shift is easily observed in the spectrum of an oxidized form of the heterogeneous PEGylated protein. Ion mobility separations can fractionate PEGs of different chain length; when coupled with charge stripping ion/molecule reactions, ion mobility mass spectrometry (IMMS) offers several analytical advantages over mass spectrometry alone for the characterization of large PEGylated molecules including enhanced dynamic range, increased sensitivity, and specificity. Low abundance free PEG in a PEGylated peptide preparation, which is not directly detectable by mass spectrometry, can be easily observed and accurately quantified with gas-phase ion/molecule chemistry combined with ion mobility mass spectrometry..[Dhanashri:2008]{Human}

[complex, mass spectrometry]
  • The reliability of different sample preparation procedures, including solvent-free methods, is discussed, and strategies are outlined that serve to apply the potentiality of LDI mass spectrometry to the characterization of covalent and non-covalent compounds in complex carbonaceous systems..[Bruno:2007]

[complex, molecular weight, studied]
  • Hence, either nonspecific aggregation occurred here, or the modification enzymes studied are not members of the aminoacyl-tRNA synthetase complex in E. coli. These findings do suggest that some bacterial tRNA modification enzymes are present in multiprotein complexes of high molecular weight..[Harris:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • At constant protein concentration, results were also linearly correlated with the size of the aggregates in the lower molecular weight fractions, although the number of aggregates in the fractions decreased with increasing molecular weight. It is concluded that results in these assays can only be compared with respect to concentration if the immune complexes have identical sizes. Consequently, we studied the relative affinity of C1q and monoclonal rheumatoid factor for antigen/antibody immune complexes of different sizes or different antigen/antibody ratios, using model immune complexes composed of tetanus toxoid/anti-toxoid and streptolysine O/anti-streptolysine O. Compared to C1q, monoclonal rheumatoid factor was found to have higher affinity for smaller complexes, and for complexes with higher antigen/antibody ratio..[Vanham:1985]{Human}

[a mass, molecular weight]
  • In addition, this mobile phase allowed the coupling of SEC to a mass spectrometer to obtain a direct molecular weight measurement..[Hongcheng:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Chemical information, such as molecular weight and MS/MS fingerprint, was obtained in real time by directing part of the HPLC effluent towards a mass spectrometer. Using this approach in total three estrogenic compounds, i.e. luteolin, quercetin and kaempferol, were detected and identified by comparing the obtained molecular weights and negative ion APCI MS/MS spectra with the data of an estrogenic compound library..[Danny:2004]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, spectrometry, weight]
  • Isothermal thermal gravimetric analysis reveals a 3% decrease in weight over 20 h of aging at 250 degrees C. Degraded samples also were analyzed by traditional solid-state (1)H NMR techniques, and off-gassing products were identified by solid-phase microextraction followed by gas chromatography-mass spectrometry. The results, which will be discussed here, suggest that thermal degradation proceeds by complex competition between oxidative chain scissioning and postcuring cross-linking that both contribute to embrittlement..[Jason:2007]

[been, molecular weights]
  • Several low-molecular-weight glycans (degree of polymerization up to 13) were observed whose structures have already been elucidated. In addition, a variety of so far unknown large-sized carbohydrates was detected whose molecular weights range from M(r) 2242 to 8000..[Stahl:1995]{Human}

[macromolecular, molecular/molecular mass]
  • This study explores the potential of a novel electrospray-based method, termed gas-phase electrophoretic mobility molecular analysis (GEMMA), allowing the molecular mass determination of peptides, proteins and noncovalent biocomplexes up to 2 MDa (dimer of immunglobulin M). The macromolecular ions were formed by nano electrospray ionization (ESI) in the 'cone jet' mode..[Bacher:2001]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complex/complexes, mass/mass spectrometry, molecular weight/molecular weights]
  • As part of an effort to develop a general, sensitive mass spectrometric strategy for the characterization of protein-nucleic acid interactions, we have used matrix-assisted laser desorption-ionization (MALDI) time-of-flight mass spectrometry to analyze protein-nucleic acid complexes that have been covalently crosslinked by ultraviolet (UV) light. In general, the application of MALDI mass spectrometric techniques to studies of UV-induced crosslinking of nucleoprotein complexes is demonstrated to be feasible. Specifically, MALDI mass analysis was used to determine the molecular weights of the phage T4 gene 32 protein (gp32) crosslinked to the oligonucleotide (dT)20, and the Escherichia coli transcription termination factor rho, photoaffinity labeled with 4-thio-uridine-diphosphate (4sUDP). The covalent gp32:(dT)20 complex is readily detected at a concentration of 1-2 microM in 1 microL of an unpurified solution of reactants that has been exposed to a single, 266 nm UV laser pulse. Mass spectrometric molecular weight determinations of the covalent rho:4sUDP complex add directness and specificity to the ATPase inactivation assay normally used to monitor the formation of 4sUDP photoaffinity labeled rho. It is found that successful MALDI mass spectrometry of protein-nucleic acid complexes is as critically dependent on the choice of solvents and additives as it is on the primary matrix compound..[Jensen:1993]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complexes, a mass/mass spectrometry, molecular weight/molecular weights]
  • This study presents a novel method for determining the molecular weights of low molecular weight (MW) energetic compounds through their complexes of beta-cyclodextrin (beta-CD) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in a mass range of 500 to 1700 Da, avoiding matrix interference..[Min:2006]

[large, molecular weight/molecular weights, weight]
  • The molecular weights of individual ions whose charge state shifted during reaction were determined with an accuracy of 67 ppm, the first example of using an individual-ion approach to the determination of molecular weight for a large biopolymer. The molecular weight distribution of a group of ions can be determined with a precision related to the number of ions examined and the weight heterogeneity of the sample. We obtained the molecular weight for eight individual ions from which a molecular weight of 133,320 +/- 210 Da was calculated for bovine albumin dimer..[Cheng:1994]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been studied, molecular weight/molecular weights, studied]
  • Thermal degradation of a filled, cross-linked siloxane material synthesized from poly(dimethylsiloxane) chains of three different average molecular weights and with two different cross-linking species has been studied by (1)H multiple quantum (MQ) NMR methods. Multiple domains of polymer chains were detected by MQ NMR exhibiting residual dipolar coupling (<Omega(d)>) values of 200 and 600 Hz, corresponding to chains with high average molecular weight between cross-links and chains with low average molecular weight between cross-links or near the multifunctional cross-linking sites. Characterization of the <Omega(d)> values and changes in <Omega(d)> distributions present in the material were studied as a function of time at 250 degrees C and indicate significant time-dependent degradation..[Jason:2007]

[been, mass, molecular weights/weights]
  • For the polydispersed asphaltenes from two different crude oils, MWDs peaking at masses smaller than 500 amu with a high-mass tail extending up to about 3000 amu have been observed, yielding average weights around 900 amu. Such MWDs are in good agreement with previous mass spectrometric measurement, as well as with diffusion studies in solution. In addition, stable asphaltene aggregates have been detected giving rise to two broad bands in the mass spectrum corresponding to average molecular weights of 2200-3100 amu and 15,000-19,000 amu, respectively..[Bruno:2007]

[analysed, mass/mass spectrometry, molecular]
  • Three peptides isolated from the atrial glands of Aplysia californica were analysed by Fast Atom Bombardment Mass Spectrometry. Survey scans over the mass range 1650 to 7500 at 500 resolution were used to locate signals for the protonated molecular ion and two subunits which result from cleavage of a single disulfide bond. A more accurate mass determination was made by accumulating scans over a narrow mass range..[Lee:1985]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[intact, mass/mass spectrometry, molecular weight/molecular weights]
  • Analysis of mGST 1 and mGST 2 by electrospray ionization mass spectrometry determined their molecular weights to be 17,354.2 +/- 6.6 and 17,397.9 +/- 6.6, respectively. mGST 1 was in close agreement with the calculated molecular weight of 17,348, as predicted by the previously reported cDNA sequence. Cyanogen bromide digestion and peptide mapping by fast atom bombardment mass spectrometry (FAB-MS) localized the mass increase to the N-terminal peptide, 1-7. FAB-tandem mass spectrometry of this peptide in conjunction with Edman reactions on the intact protein demonstrated the N-terminal alanine to be acetylated..[Shore:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [intact, mass spectrometry, molecular weights]
    • First, the accurate molecular weights of the intact and tetra-S-carboxymethylated Paim I are determined by fast atom bombardment mass spectrometry..[Hirayama:1988]{Human}

[molecular weight, studied]
  • Purines, pyrimidines, pteridines, and nucleosides represent some of the compound classes which are studied repeatedly in our laboratory. Often the primary information sought is the molecular weight..[Brent:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[molecular weight studied]
  • Results showed that FD fluxes were the same in both apical-to-basolateral (AB) and opposite (BA) directions at each molecular weight studied..[Matsukawa:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complexes, intact]
  • However, large-pore gel filtration chromatography could be used to separate intact poly(A)-PABP complexes from free PABP..[Drawbridge:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Complex 4 is less well-characterized, but its intact structure is projected to consist of YXD and DXY fragments from adjacent fibrin strands. Each complex is heterogeneous in subunit composition, reflecting additional plasmin cleavages within and/or adjacent to its theoretical boundaries. Since most of the protein initially released into solution from degrading fibrin is as complexes larger than DD/E, the derivatives described in this report are likely to be major circulating degradation products of crosslinked fibrin in vivo..[Francis:1981]{Human}

[molecular weights]
  • The molecular weights of these subpeptides are determined by FABMS. The peptides that must be sequenced are selected by the molecular weights of these subpeptides and the tetra-S-carboxymethylated Paim I..[Hirayama:1988]{Human}
  • In contrast, molecular weights resulted from external calibration using dextran and pullullan standards showed drastically different numbers. Therefore, the GFC-MALDI-MS approach is a reliable method for the molecular weight characterization of polydisperse polysaccharides for which suitable calibration standards are unavailable for conventional GFC analysis..[Yeung:1999]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • While the molecular weights determined with MALDI-TOF-MS were most accurate, both gel electrophoretic methods provided molecular weights that were too high because of the attached glycan structures..[M?ller:2007]{Human}
  • Proteins with molecular weights of <25 kDa are involved in major biological processes such as ribosome formation, stress adaption (e.g., temperature reduction) and cell cycle control..[Stephan:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, mass, molecular weight/molecular weights]
  • Resolved isotopic peaks were observed for porphyrins with molecular weights below 1000, and unresolved isotopic peaks yielding average masses were observed for porphyrin compounds with higher molecular weights. The limited resolution in the higher molecular weight range does not lessen the utility of the method because the observation of the molecule ions [M.+ and/or (M+H)+] provides unambiguous evidence concerning the success of the synthesis. The 252Cf plasma desorption mass spectra of porphyrins are not complicated by chemical transformations. This method is ideally suited for rapid analysis of synthetic porphyrins and provides a powerful tool for chemists engaged in the synthesis of complex organic molecules..[Lindsey:1993]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Positive-ion spectra for each FA obtained under optimum conditions resulted in number-average molecular weights ranging from 1700 to 1900. The mass spectra were extremely complex, with ion distributions on the order of m/z approximately 500-3000. The presence of more than one ion at each nominal mass was routinely observed..[Brown:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[large, spectrometry]
  • The methods are based on pyrolysis (Py) performed in a programmed-temperature vaporization injector with subsequent identification and quantification of the components in the pyrolysate using capillary gas chromatography-mass spectrometry (GC-MS). By injecting large volumes and applying cryo-focussing at the top of the column, low detection limits could be achieved..[Aleksandra:2011]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complex/complexes, mass/mass spectrometry, molecular weight/molecular weights]
  • Molecular weights of heparin-derived oligosaccharides ranging from disaccharides to hexadecasaccharides have been determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. While these compounds ionize poorly or not at all when used as such, a strong signal can be obtained of their ionic complexes formed with a basic peptide or protein. The molecular weight of the sulfated oligosaccharide is determined by subtracting the mass of the basic component from that of the complex..[Juhasz:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [been, complexes, mass spectrometry, molecular weight/molecular weights]
    • The complexes cis-chloro(phenyl)(dppp)nickel(II) and cis-chloro(o-tolyl)(dppp)nickel(II) were synthesized and characterized by (31)P NMR spectroscopy. These complexes served as initiators in the polymerization of 2-bromo-5-chloromagnesio-3-hexylthiophene in THF at room temperature, affording fully regioregular P3HT with controlled molecular weights and narrow molecular weight distributions, as demonstrated by gel-permeation chromatography and (1)H NMR spectroscopy. MALDI-TOF mass spectrometry revealed that the polymers had almost complete incorporation of the initiating aryl group, and when the aryl group was o-tolyl, only Tol/H end groups were observed. Although external initiators have been used previously with a PPh(3) ligand, that methodology led to polymers with broad molecular weight distributions. This is the first example in which complete control over the externally initiated P3HT polymerization has been achieved..[Hugo:2009]

[been studied, complex, mol/molecular weights]
  • The interaction between three poly(9,9-bis(6-N,N,N-trimethylammonium)hexyl)fluorene phenylene) bromide (HTMA-PFP) samples of different molecular weights (Mn=14.5, 30.1 and 61.3 kg/ mol) and both dsDNA and ssDNA secondary structures has been studied using UV-visible absorption and fluorescence spectroscopies (including steady-state, time-resolved, and anisotropy measurements for the latter), viscosity, and electrical conductivity in 4% (v/v) DMSO-water mixtures. At low nucleic acid concentrations, formation of a 1:1 complex in terms of HTMA-PFP repeat units and DNA bases occurs..[Mar?a:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, molecular weight]
  • However, by reversing the titration and adding thrombin to fluorescein-heparin the dissociation constant for complex 2 was estimated to be 1-3 microM and independent of the heparin molecular weight. The complex formed between thrombin and heparin, to which antithrombin was attached, has a dissociation constant of 1-2 microM, again irrespective of the heparin molecular weight..[Evington:1986]{Human}
  • The stabilities of the complexes depend mainly on the molecular weight of the guest molecules, a fact suggesting that the complexes collapse in the gas phase..[Pim:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Gel electrophoresis of the crosslinked complexes in sodium dodecyl sulfate revealed a new protein band with an apparent molecular weight of 38 K..[Birchmeier:1977]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Molecular weight and electric charge of the macromolecules significantly affected their disposition characteristics and, consequently, determined radioactivity accumulation in the tumor. It was concluded that a drug-carrier complex designed for systemic tumor targeting should be polyanionic in nature and larger than 70,000 in molecular weight..[Takakura:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The results showed that the observed relationship between strength and molecular weight was more complex than that used in our model. However, the data could be modelled using an empirically derived relationship between tensile strength and number average molecular weight (Mn)..[Farrar:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[analysed, molecular weight/molecular weights]
  • Size-exclusion chromatography (SEC) and Py-GC-MS were used to measure molecular weights and average chemical compositions, respectively. Combined off-line SEC//Py-GC-MS was used to determine the copolymer composition (VP/VA ratio), as a function of the molecular weight for the pure polymers. In the dissolution experiments, a constant VP/VA ratio across the dissolution curve was observed for all copolymers analysed..[Aleksandra:2011]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been studied, mass]
  • Ion-molecule reactions of individual multiply-protonated ions of bovine albumin dimer, formed from electrospray ionization, have been studied using a Fourier transform ion cyclotron resonance mass spectrometer..[Cheng:1994]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[a mass/mass spectrometry, molecular weight/molecular weights, studied]
  • The plasma desorption mass spectrometry method is used to determine the molecular weights of larger molecules than before, to determine the molecular weights of proteins and peptides in mixtures, and to monitor protein modification reactions. Proteins up to molecular weight 25,000 can now be studied with a mass spectrometric technique..[Sundqvist:1984]{Human}

[intact, molecular weight/molecular weights]
  • To search for molecular weights of mature proteins in the National Center for Biotechnology Information (NCBI) database, a new feature was developed and its applicability tested. The identification of a class of pathogenic virulence proteins, either intact or digested, is possible with molecular weight database searching..[Sonja:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[intact, large]
  • Moreover, these FDs were found to be relatively intact (approximately 90%) in either receiver fluid after 5-h flux experiments without detectable levels of metabolites in the respective donor fluid, suggesting that alveolar epithelial cells allow translocation of FDs intact across the barrier. Equivalent pore analysis, assuming restricted diffusion of FDs of 4-40 kDa via cylindrical, water-filled pores across the cell monolayer revealed a population of large equivalent pores with approximately 5.6 nm radius..[Matsukawa:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been studied, molecular]
  • The molecular basis for human group IIA phospholipase A(2) inactivation by the marine natural product cladocoran A (CLD A) has been studied in order to elucidate its relevant anti-inflammatory properties..[Maria:2011]

[mass, molecular weight/molecular weights]
  • Measured mass values are within 0.5 amu of calculated average molecular weights. Results illustrate the utility of the technique for accurate molecular weight determinations on limited quantities of high molecular weight peptides..[Lee:1985]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Initial results combining rapid separations by capillary zone electrophoresis with on-line mass spectrometric detection via the electrospray ionization source are demonstrated for myoglobin and other proteins and polypeptides. The potential for extension of these methods to molecular weights on the order of 10(6) is discussed..[Loo:1989]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, spectrometry]
  • More than 20 different colonization factors have been described so far using predominantly immunological and genetic methods. To characterize these hydrophobic proteins by liquid chromatography-mass spectrometry (LC-MS), different methodologies were explored..[Sonja:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complexes, great]
  • Our results demonstrate that ESI-MS is a powerful tool to analyze supramolecular ssDNA complexes in great detail..[Pim:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[molecular mass]
  • This work demonstrates the use of maximum entropy in the assessment of protein content and in the subsequent resolution enhancement of naturally occurring protein mixtures containing components of closely similar molecular mass..[Evershed:1993]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Molecular mass determinations of calbindin delta 2,6 showed that this protein contains a highly active cysteine residue that covalently binds a mercaptoethanol group, or forms a homodimer via a disulfide bond..[Johnson:1999]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, mass spectrometry, molecular weight/molecular weights]
  • We have used on-line sample clean-up, concentration, and chromatography with electrospray ionization mass spectrometry (ESI-MS), to characterize and determine the presence of disulfide bonds in recombinant full-length rat brain calbindin D28K and two deletion mutants of the protein, one lacking EF-hand 2 (calbindin delta 2) and the other lacking EF-hands 2 and 6 (calbindin delta 2,6). The molecular weights of the expressed proteins dissolved in biological buffers were determined with high accuracy using a low-flow, pressurized chamber infusion system, that allows on-line protein clean-up by removing buffers/salts incompatible with ESI-MS. The molecular weight determinations showed that the amino-terminal methionine residues had been cleaved during the expression and isolation of the recombinant proteins..[Johnson:1999]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Several odorant-binding proteins (OBP) have been previously purified from the nasal mucosa of the old world porcupine Hystrix cristata. In this paper, we report their N-terminal amino-acid sequences and accurate molecular weights, as measured by electrospray mass spectrometry..[Ganni:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, mass/mass spectrometry, molecular weight/molecular weights]
  • The use of UV-absorbing molecules as matrices in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is well documented. The matrices that are currently used have low molecular weights (<300 Da) and thus, for a typical MALDI-TOF spectrum, the low-mass range (m/z 100-500) is dominated by matrix ions. Consequently, the applications of MALDI-TOFMS have been restricted mostly to the analysis of high molecular weight analytes. This report demonstrates the use of meso-tetrakis(pentafluorophenyl)porphyrin (F20TPP, MW 974.57) as a matrix in the MALDI-TOF mass spectrometric analysis of some commercial nonylphenol ethoxylates (4-(C(9)H(19))-C(6)H(4)-(OCH(2)CH(2))(n)-OH), in which the ethoxymer ion distribution ranges from 331-771 Da..[null:2000]

[large, mass]
  • By combining native mass and subunit composition data, structural models can be proposed for large edifices such as annelid extracellular hexagonal bilayer hemoglobins (HBL Hb) and crustacean hemocyanins (Hc)..[Matthieu:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • We demonstrate that the method is particularly useful for the characterization of large phosphopeptides, including those with multiple phosphorylation sites, as extensive series of c' and z fragment-ions were observed. Finally, we have applied a directed tandem mass spectrometric workflow using inclusion lists to increase the number of identified peptides..[Bruno:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, complexes]
  • The presence of high-molecular-weight complexes of aminoacyl-tRNA synthetases in Escherichia coli has been reported (C..[Harris:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been/been studied, molecular weight/molecular weights]
  • Poly(A)-binding proteins (PABPs) are the best characterized messenger RNA-binding proteins of eucaryotic cells and have been identified in diverse organisms such as mammals and yeasts. The in vitro poly(A)-binding properties of these proteins have been studied intensively; however, little is known about their function in cells. In this report, we show that sea urchin eggs have two molecular weight forms of PABP ( molecular weights of 66,000 and 80,000)..[Drawbridge:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [been, molecular weight]
    • Solution parameters which have been reported to affect molecular weight distributions of FA such as pH, ionic strength, and concentration of multivalent cations were found to have little or no effect on the observed m/z distributions..[Brown:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
    • BH(3) (7), to yield the soluble, high molecular weight poly(N-methylaminoborane) (8a), [MeNH-BH(2)](n) (M(W) > 20? 000), has been achieved at 20 ?.[Anne:2010]

[large, studied]
  • The technique represents an important contribution to structural studies on peptides, since (i) blocked peptides may be studied, (ii) no prior formation of chemical derivatives is necessary (except for distinction between lysine and glutamine), (iii) sensitivity is good, (iv) large peptides, and, in some cases, mixtures of peptides, can be studied, and (v) the technique is easy to operate, with ions being produced over a long period (5-30 min)..[Williams:1982]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, mass]
  • Proteome-wide characterization of glycoproteins is a complex task and is currently achieved by mass spectrometry-based methods that enable identification of glycoproteins and localization, classification, and analysis of individual glycan structures on proteins..[David:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[mass, molecular/molecular weight/molecular weights]
  • At mass resolving powers between 60,000 (high mass) and 120,000 (low mass), it was possible to determine that virtually all ions present in spectra of Suwannee River fulvic and humic acid are singly charged, thus eliminating inadequate accounting for multiply charged ions as a primary source of any low molecular weight bias. The high-resolution mass spectra also revealed the presence of molecular families containing ions that differ from each other in degree of saturation, functional group substitution (primarily CH vs N and CH4 vs O), and number of CH2 groups. Ionization suppression and ion fragmentation were addressed for humic and fulvic acid mixtures and well-characterized poly(ethylene glycol) (PEG) mixtures with average molecular weights of 8000 and 10,000. Although these high molecular weight PEG mixtures fragment extensively under traditional positive-ion mode ESI conditions, similar fragmentation could not be confirmed for humic and fulvic acid mixtures..[Alexandra:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • For a second system, the molecular weight of the 45 kDa phosphopantothenoylcysteine synthetase/decarboxylase (CoaBC), an enzyme involved in Coenzyme A biosynthesis, was 131 Da lower than that of the DNA prediction; the ECD spectrum showed that this is due to the removal of the N-terminal Met. For a third system, viral prolyl 4-hydroxylase (26 kDa), ECD showed that multiple molecular ions (+98, +178, etc.) are due to phosphate noncovalent adducts, and MS/MS pinpointed the overall mass discrepancy of 135 Da to removal of the initiation Met (131 Da) and to formation of disulfide bonds (2 x 2 Da) at C32-C49 and C143-C147, although 10 S-S positions were possible..[Ying:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [mass, molecular weight]
    • With the apparent advantages of unsurpassed mass accuracy, low dependence on the physicochemical properties of the surface layer proteins, and high sensitivity, it can be concluded that a linear time-of-flight instrument combined with UV matrix-assisted laser desorption with concomitant ionization is better suited for molecular weight determination than is gel electrophoresis..[Allmaier:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
    • A comparison of the mass spectrometric data with those obtained when alpha-cyano-4-hydroxycinnamic acid (CHCA) was used as the matrix indicated that the F20TPP-induced spectra provided comparable data, with the advantage of having less matrix interference in the low-mass range (m/z 100-500). Thus, the use of F20TPP and similar porphyrins may provide the means to apply MALDI-TOF to the analysis of low molecular weight molecules with minimum interference from matrix signals..[null:2000]
    • Here we investigated biochemical and mass spectrometric parameters that influence coverage and validity of identification. The underrepresentation of low molecular weight (LMW) proteins may be attributed to the low numbers of proteolytic peptides formed by tryptic digestion as well as their tendency to be lost in protein separation and concentration/desalting procedures..[Stephan:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[advanced mass spectrometry, molecular]
  • Our results, collected by a combination of biochemical approaches, advanced mass spectrometry and molecular modeling, suggest a competitive inhibition mechanism guided by a noncovalent molecular recognition event, and disclose the key role of the CLD A γ-hydroxybutenolide ring in the chelation of the catalytic calcium ion inside the enzyme active site..[Maria:2011]

[advanced mass spectrometry/mass spectrometry, molecular]
  • In cancer and autoimmune diseases, immunoglobulins with a specific molecular signature that could potentially be used as diagnostic or prognostic markers are released into body fluids. An immunomics approach based on this phenomenon relies on the ability to identify the specific amino acid sequences of the complementarity-determining regions (CDR) of these immunoglobulins, which in turn depends on the level of accuracy, resolution, and sensitivity that can be achieved by advanced mass spectrometry. Reproducible isolation and sequencing of antibody fragments (e.g., Fab) by high-resolution mass spectrometry (MS) from seven healthy donors revealed 43 217 MS signals: 225 could be associated with CDR1 peptides, 513 with CDR2 peptides, and 19 with CDR3 peptides..[Dominique:2010]{Human}

[complex, molecular weight/molecular weights]
  • Stabilized aggregates of human IgG were prepared over a wide range of molecular weights. These fractions with increasing molecular weight were adjusted to the same molarity or the same protein concentration and were tested in the solid phase C1q and monoclonal rheumatoid factor immune complex assays..[Vanham:1985]{Human}
  • Iron-regulated outer membrane proteins (IROMPs) of P. multocida serotype A3, which function as receptors for complexes containing iron ions, are induced by iron deficiency in the bacterial growth environment. Analysis of an electrophoresis image of proteins isolated from bacteria grown on medium supplemented with 2,2'-dipyridyl revealed expression of 16 new proteins that were not noted in the case of the bacteria grown in standard conditions, with molecular weights from 30 to 160 kDa..[Puchalski:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • In the current study, Bio-Gel A-5M gel chromatography of 105,000 x g supernatant preparations from E. coli Q13 indicated high molecular weights for both tRNA methylase (300,000) and tRNA sulfurtransferase (450,000). These tRNA modification enzymes did not appear to exist in the same multienzymic complex..[Harris:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[large, mass/mass spectrometry]
  • The ability of electrospray ionization (ESI) to effectively transfer large ions from the solution phase to the gas phase and the coupling of ESI to the high-mass-resolution capabilities of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provide a potential method for the mass spectrometric analysis of FA..[Brown:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complex, macromolecular assemblies/molecular]
  • Moreover, recent findings will be discussed showing that molecular models of proteins can be fitted into depicted organellar ultrastructure of images of frozen hydrated sections. High pressure freezing of tissue is the base which may lead to precise models of macromolecular assemblies in situ, and thus to a better understanding of the function of complex cellular structures..[Daniel:2008]{Human}

[molecular weight/molecular weights]
  • Only amylopectin ( molecular weight, greater than 25,000) was excluded in transport experiments, whereas maltodextrins with molecular weights of up to 2,000 were not excluded by the presence of an O-polysaccharide layer..[Ferenci:1986]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • This data was used to generate a 2-D pI-MS protein map, where proteins are displayed according to their pI and molecular weight. Protein molecular weight peaks are represented as bands in the 2-D pI-MS image where the gray scale of each band is proportional to the intensity of the protein molecular weight peak..[Wall:2001]{Human}
  • Both this predefined pTyr proteome subset and the total cell lysates were then used as sample sources to identify potential substrates of dPTP61F, the smallest member in terms of amino acid number and molecular weight in the Drosophila PTP family and the ortholog of human PTP1B and T Cell-PTP, by substrate trapping..[Ying-Che:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The identified membrane proteins provide a broad representation of the rat plasma membrane proteome with little bias evident due to protein p I and molecular weight (MW)..[Rui:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The molecular weight of erinacin determined by gel filtration was approx. 1000 kDa. SDS-PAGE of erinacin under reducing conditions indicates that it consists of two types of subunits, alpha and beta, with molecular weights of 37 and 35 kDa, respectively, in a ratio of 1:2..[Omori-Satoh:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Accurate molecular weight determination on chemically homogeneous oligosaccharides (+/- 0.05%) unambiguously identified the number of saccharide units, and the number of O,N-sulfate and N-acetyl groups..[Juhasz:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • For applications of ESI-MS, the unit discusses molecular weight determination, sequencing, and analysis of oligonucleotide mixtures by LC-MS..[Colette:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • For applications of ESI-MS, the unit discusses molecular weight determination and gives protocols for sequencing and for analyzing oligonucleotide modifications..[Polo:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The FD P(app) (x 10(-8)cm/s) decreased gradually from 1.35 for FD4 to 0.32 for FD40, indicating an apparent inverse relationship between P(app) and molecular weight of FD..[Matsukawa:1997]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • With respect to the photophysical parameters (emission quantum yield, shape and shift of emission spectra), no significant differences were observed between dsDNA and ssDNA or with conjugated polymer or DNA molecular weight..[Mar?a:2009]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[mass]
  • For inhomogeneous samples larger than decasaccharides, the mass accuracy is lower (+/- 0.2-0.3%) but still suffices to determine the number of saccharide units present and to estimate the number of sulfate groups, except it is no longer possible to differentiate one sulfate from two N-acetyl groups (delta = 4 Da)..[Juhasz:1995]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[been, mass/mass spectrometry]
  • 252Cf plasma desorption mass spectrometry has been used in the characterization of more than 100 synthetic porphyrins ranging in mass from 614 u for tetraphenylporphyrin to over 2000 u for some porphyrin model systems. In virtually every case, 252Cf plasma desorption mass spectrometry yielded an intense ionized molecule ion [M.+ and/or (M+H)+], irrespective of the groups appended to the porphyrin..[Lindsey:1993]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [been, mass spectrometry]
    • In this study neutral and acidic oligosaccharide fractions prepared from human milk have been investigated using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)..[Stahl:1995]{Human}
    • During recent years, phytoestrogens have been receiving an increasing amount of interest, as several lines of evidence suggest a possible role in preventing a range of diseases, including the hormonally dependent cancers. In this context, various parts of the pomegranate fruit (Punica granatum; Punicaceae), e.g. seed oil, juice, fermented juice and peel extract, have been shown to exert suppressive effects on human breast cancer cells in vitro. On-line biochemical detection coupled to mass spectrometry (LC-BCD-MS) was applied to rapidly profile the estrogenic activity in the pomegranate peel extract..[Danny:2004]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[molecular]
  • Colorectal cancer usually develops in clearly defined stages, with distinct molecular alterations characterizing each transition..[Georgia:2009]{Human}
  • Cluster ions and background noise make it difficult to assign molecular ions, and some compounds do not yield molecular ions with FD..[Brent:1976]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The molecular recognition and inclusion behavior of beta-CD to energetic materials (EMs) were investigated..[Min:2006]

[large]
  • Glycoproteins constitute a large fraction of the proteome..[David:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • We attribute these differences to the rapid large energy input of ion-surface collisions, which leads to the dissociation of subunits prior to the unfolding of individual monomers..[Richard:2009]{Human}
  • The addition of ECD substantially increases the capabilities of top down FTMS for the detailed structural characterization of large proteins..[Ying:2002]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Normal sera contain a large number of naturally occurring autoantibodies which can mask important disease-associated ones..[Franz:2003]{Human}

[intact]
  • These differences are not readily detected by other techniques and show that ESI-MS is a powerful, rapid method by which to detect disulfide linkages for intact proteins..[Johnson:1999]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Iodination of basal-lateral plasma membranes, at a yield comparable to that obtained with apical labeling, was attained after about 30 min of exposure of the intact bladder to the labeling solutions..[Rodriguez:1979]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[integrity]
  • The present report describes high yield enzymatic radio-iodination of the apical and basal-lateral plasma membranes of toad bladder epithelium, by a procedure that does not breach the functional integrity of the epithelium, as assessed by the basal and vasopressin-sensitive short-circuit current (SCC)..[Rodriguez:1979]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[studied]
  • The method also confirmed that one inhibitor studied binds to CP88 in a reversible covalent manner..[Stone:2005]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Silver salts were found to be the best cationization reagents for all of the cases studied..[null:2000]

[mass/mass spectrometry]
  • Regarding mass spectrometry analysis with an LTQ Orbitrap mass spectrometer, collision-induced fragmentation (CID and HCD) and electron transfer dissociation using the linear ion trap (IT) or the Orbitrap as the analyzer were compared..[Stephan:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

  • [mass spectrometry]
    • Two of the applied techniques were based on gel electrophoretic separation in the liquid phase while the third technique was the gas-phase technique mass spectrometry..[M?ller:2007]{Human}
    • This ProteinChip system uses ProteinChip arrays and SELDI-TOF MS (surface-enhanced laser desorption/ionization-time of flight mass spectrometry) technology for capturing, detection, and analysis of proteins without labelling or without the need of chemical modification..[Franz:2003]{Human}

[been]
  • Of these proteins, 93 had not yet been functionally classified, and five had not previously been confirmed at the protein level..[Stephan:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}

[complexes/large complexes]
  • The binding patterns of the different fractions to solid phase C1q and monoclonal rheumatoid factor were quite variable and in only one of these sera monoclonal rheumatoid factor had the expected preference for small complexes and C1q for large complexes..[Vanham:1985]{Human}

[complex]
  • Compared to the human PA28 complex, PA26 may be the prototype activator protein involved in proteasomal protein degradation. Therefore, the MS-based strategy developed here for identification of the known and unknown protein complexes can be generalized for the study of other protein complexes..[Lan:2006]{Human}
  • The retinoid (visual) cycle is a complex enzymatic pathway essential for regeneration of the visual chromophore, 11-cis-retinal, a component of rhodopsin that undergoes activation by light in vertebrate eyes..[Marcin:2010]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Among them, 16 potential substrates were confirmed as tyrosine phosphorylated proteins, including a receptor PTK PDGF/VEGF receptor, a cytosolic PTK Abl, and several components of SCAR/WAVE complex, which may work in coordination to control actin dynamics..[Ying-Che:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • This study not only offered an efficient and powerful method in shotgun proteomics for the identification of proteins of complex plasma membrane samples but also allowed in-depth study of liver membrane proteomes, such as of rat models of liver-related disease..[Rui:2008]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • A protocol to study the binding mode of protein-ligand complexes under denaturing conditions was developed..[Stone:2005]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Here, we present results from the gas-phase dissociation of protein-protein complexes upon collision into a surface..[Richard:2009]{Human}
  • Complete inhibition was achieved in an equimolar mixture of inhibitor and enzyme suggesting an equimolar complex..[Omori-Satoh:2000]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • The 20S proteasome is a multicatalytic protein complex that plays an important role in intracellular protein degradation from archaebacteria to eukaryotes..[Lan:2006]{Human}
  • Compared to traditional screening approaches of complex mixtures, often characterized by a repeating cycle of HPLC fractionation and biological screening, LC-BCD-MS was shown to profoundly accelerate the time required for compound description and identification..[Danny:2004]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • Despite this evidence for association of the sulfurtransferase with the synthetase complex, isoleucyl-tRNA synthetase and tRNA sulfurtransferase were totally resolved from each other by DEAE-Sephacel chromatography..[Harris:1990]{Non-Human,Non-Trail,Non-Review,Non-Guidline}
  • These results demonstrate that, in some cases, electrostatic noncovalent protein complexes can survive the denaturing conditions of reversed phase liquid chromatography and the gas phase transfer occurring during electrospray ionization..[Catalin:2004]{Human}