Gas‐Flüssigkeits‐Chromatographie und Massenspektrometrie bei der Methylierungsanalyse von Polysacchariden
TL;DR: In this article, the kombinierte Anwendung von Gas-Flussigkeits-Chromatographie und Massenspektrometrie zur Analyse der Gemische methylierter Zucker gestatten es, die Methylierungsanalyse von Polysacchariden genauer, schneller und mit weniger Material als bisher durchzufuhren.
Abstract: Neue Methylierungsmethoden und die kombinierte Anwendung von Gas-Flussigkeits-Chromatographie und Massenspektrometrie zur Analyse der Gemische methylierter Zucker gestatten es, die Methylierungsanalyse von Polysacchariden genauer, schneller und mit weniger Material als bisher durchzufuhren.
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TL;DR: In this paper, the molar flame-responses of partially methylated partially ethylated alditol acetates were measured and compared to the predicted values from three theories: equal molar response, equal weight response, effective carbon response.
728 citations
TL;DR: Analysis of the irregular xylem 9 (irx9) mutant of Arabidopsis revealed a decrease in the abundance of xylan in the mutant, indicating that the IRX9 gene, which encodes a putative family 43 glycosyltransferase, is required for xylan synthesis.
Abstract: To facilitate analysis of plant cell wall polysaccharide structure and composition, we cloned 74 genes encoding polysaccharide-degrading enzymes from Aspergillus nidulans, Aspergillus fumigatus, and Neurospora crassa and expressed the genes as secreted proteins with C-terminal Myc and 6x His tags. Most of the recombinant enzymes were active in enzyme assays, and optima for pH and temperature were established. A subset of the enzymes was used to fragment polysaccharides from the irregular xylem 9 (irx9) mutant of Arabidopsis. The analysis revealed a decrease in the abundance of xylan in the mutant, indicating that the IRX9 gene, which encodes a putative family 43 glycosyltransferase, is required for xylan synthesis.
316 citations
01 Jan 1971
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TL;DR: The data obtained by methylation analysis and nuclear magnetic resonance spectroscopy indicated that the repeating sequence of the capsular polysaccharide is the 4-β-glucuronyl-1,4-α-N-acetylglucosaminyl unit, similar to that of desulfo-heparin.
Abstract: The capsular polysaccharide was isolated from Escherichia coli 010:K5:H4; it could not be obtained from a uncapsulated (K5-) mutant. It contains N-acetylglucosamine and glucuronic acid in a molar ratio of 1:1. Acid hydrolysis of the acidic polysaccharide as well as Smith degradation and degradation by deamination of the carboxyl-reduced polysaccharide suggested that the polysaccharide is composed of a disaccharide repeating unit. The data obtained by methylation analysis and nuclear magnetic resonance spectroscopy indicated that the repeating sequence of the capsular polysaccharide is the 4-beta-glucuronyl-1,4-alpha-N-acetylglucosaminyl unit. This structure is similar to that of desulfo-heparin.
289 citations
TL;DR: It was shown that allolactose could also be formed in significant quantities by the transfer of galactose to the 6 position of free glucose, and also by hydrolysis of preformed trisaccharide, and the mechanism which fits the initial velocity data was proposed.
Abstract: A study was implemented to quantitate the hydrolase and transgalactosylase activities of beta-galactosidase (E. coli) with lactose as the substrate and to investigate various factors which affect these activities. At low lactose concentrations the rate of galactose production was equal to the rate of glucose production. The rate of galactose production relative to glucose, however, dropped dramatically at lactose concentrations higher than 0.05 M and production of trisaccharides and tetrasaccharides began (galactose/glucose ratios of about 2:1 and 3:1, respectively, were found for these two types of oligosaccharides). At least five different trissacharides were formed and their patterns of formation showed that they probably utilized both lactose and allolactose as galactosyl acceptors. Allolactose was produced in amounts proportional to glucose at all lactose concentrations (ratios of allolactose/glucose were about 0.88). Analyses of various data, including a reaction analyzed at very early times, showed that the major means of production of allolactose (and the only means initially) was the direct enzymatic transfer of galactose from the 4 position to the 6 position of the glucose moiety of lactose without prior release of glucose from the enzyme. It was shown, however, that allolactose could also be formed in significant quantities by the transfer of galactose to the 6 position of free glucose, and also by hydrolysis of preformed trisaccharide. A mechanism which fits the initial velocity data was proposed in which the steps involving the formation of an enzyme-gallactose-glucose complex, the formation and breakage of allolactose on the enzyme, and the release of glucose all seem to be of roughly equal magnitude and rate determining. Various factors affected the amounts of transgalactosylase and hydrolase activities occurring. At high pH values (greater than 7.8) the transgalactosylase/hydrolyase activity ratio increased dramatically while it decreased at low pH values (less than 6.0). At mid pH values the ratio was essentially constant. The absence of Mg2+ caused a large decrease in the transgalactosylase/hydrolase activity ratio while the absence of all but traces of Na+ or K+ had no effect. The anomeric configuration of lactose altered the transgalactosylase/hydrolase activity ratios, alpha-Lactose resulted in a decrease of allolactose production (transgalactosylase activity) relative to hydrolase activities (glucose production) while beta-lactose had the opposite effect.
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TL;DR: The mass spectra of a number of partially methylated alditol acetates, derived from methyl ethers of pentoses, hexoses, and 6-deoxyhexoses by reduction and acetylation, have been determined as mentioned in this paper.
453 citations
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TL;DR: The structure of the O-specific side-chains of the cell-wall lipopolysaccharide of Salmonella typhimurium 395 MS has been investigated and a detailed structure ofThe repeating unit of these side- chains is presented.
265 citations