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Archives of Microbiology 1993Plant cell wall polysaccharides are primarily composed of hexose or hexose derivatives, but a significant fraction is hemicellulose which contains pentose sugars....
Plant cell wall polysaccharides are primarily composed of hexose or hexose derivatives, but a significant fraction is hemicellulose which contains pentose sugars. Prevotella ruminicola B14, a predominant ruminal bacterium, simultaneously metabolized pentoses and glucose or maltose, but the organism preferentially fermented pentoses over cellobiose and preferred xylose to sucrose. Xylose and arabinose transport at either low (2 microM) or high (1 mM) substrate concentrations were observed only in the presence of sodium and if oxygen was excluded during the harvest and assay procedures. An artificial electrical potential (delta psi) or chemical gradient of sodium (delta pNa) drove transport in anaerobically prepared membrane vesicles. Because (i) transport was electrogenic, (ii) a delta pNa drove uptake, and (iii) the number of sodium binding sites was approximately 1, it appeared that P. ruminicola possessed pentose/sodium support mechanisms for the transport of arabinose and xylose at low substrate concentrations. Pentose uptake exhibited a low affinity for xylose or arabinose (> 300 microM), and transport of xylose exhibited bi-phasic kinetics which suggested that a second sodium-dependent xylose transport system was present. Little study has been made on solute transport by Prevotella (Bacteroides) species and this work represents the first use of isolated membrane vesicles from these organisms.
Topics: Animals; Arabinose; Bacteroides; Cellobiose; Glucose; Ion Transport; Rumen; Xylose
PubMed: 8484709
DOI: 10.1007/BF00288595 -
Journal of Theoretical Biology Mar 1995Simple and complete models of the classical liver pentose cycle, and a model of Williams' proposed "L-type" pentose cycle, are compared. All extant experimental data on... (Comparative Study)
Comparative Study
Simple and complete models of the classical liver pentose cycle, and a model of Williams' proposed "L-type" pentose cycle, are compared. All extant experimental data on well-oxygenated whole cell systems can be fitted to the predicted output of the complete classical pentose cycle model; however, there are gross discrepancies between key experimental data and Williams' proposed scheme. The complete classical model allows isotopic reversibility in the non-oxidative segment of the cycle, but none of the reversible enzymes are extremely close to isotopic equilibrium. General approaches are presented to estimate the isotopic reversibility of most enzymic steps, without requiring isolation of the intermediates, present in some cases at very low concentrations. The isotopic reversibility of the non-oxidative pathway causes only minor errors in the equations used to estimate liver pentose cycle flux, which were based on simple unidirectional models.
Topics: Animals; Computer Simulation; Glucose; Isotopes; Lactates; Liver; Mathematics; Models, Biological; Pentoses; Xylitol
PubMed: 7739219
DOI: 10.1006/jtbi.1995.0055 -
Pharmacology 1974
Topics: Adult; Contraceptives, Oral; Erythrocytes; Female; Glucose Tolerance Test; Humans; Leukocytes; Pentoses; Transketolase
PubMed: 4829290
DOI: 10.1159/000136475 -
Agressologie: Revue Internationale de... 1966
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The Analyst Apr 2023Differentiation of stereoisomers that are only dissimilar in the orientation of chemical bonds in space by mass spectrometry remains challenging. Structural...
Differentiation of stereoisomers that are only dissimilar in the orientation of chemical bonds in space by mass spectrometry remains challenging. Structural determination of carbohydrates by mass spectrometry is difficult, mainly due to the large number of stereoisomers in carbohydrates. Arabinose and xylose are pentose stereoisomers typically present in plant polysaccharides and exist in α- and β-anomeric configurations of furanose and pyranose forms. Conventional methods used to determine the structures of polysaccharides include hydrolysis of polysaccharides into oligosaccharides followed by identification of these oligosaccharides' structures individually through nuclear magnetic resonance spectroscopy (NMR). Although the sensitivity of mass spectrometry is much higher than that of NMR, conventional mass spectrometry provides only limited useful information on oligosaccharide structure determination, only the linkage positions of glycosidic bonds. In this study, we demonstrated a mass spectrometry method for the identification of linkage positions, anomeric configurations, and monosaccharide stereoisomers of intact oligosaccharides consisting of arabinose and xylose. We separated arabinose and xylose monosaccharides into α-furanose, β-furanose, α-pyranose, and β-pyranose forms through high-performance liquid chromatography and obtained the corresponding collision-induced dissociation mass spectra. Using these monosaccharide spectra and a flow chart consisting of the proper CID sequences derived from the dissociation mechanisms of pentose, a simple multi-stage tandem mass spectrometry method for structural identification of intact oligosaccharides consisting of arabinose and xylose was developed. The new mass spectrometry method provides a simple method for determining the structure of polysaccharides consisting of arabinose and xylose. The flow chart can be used in computer coding for automation, an ultimate goal for oligosaccharide structure determination.
Topics: Tandem Mass Spectrometry; Pentoses; Arabinose; Xylose; Oligosaccharides; Polysaccharides
PubMed: 36929945
DOI: 10.1039/d3an00068k -
Methods in Enzymology 1975
Topics: Alcohol Oxidoreductases; Chromatography, Ion Exchange; Enterobacter; Enzyme Induction; Methods; Mutation; Pentoses
PubMed: 1168836
DOI: 10.1016/s0076-6879(75)41026-6 -
Brazilian Journal of Microbiology :... 2018For the implementation of cellulosic ethanol technology, the maximum use of lignocellulosic materials is important to increase efficiency and to reduce costs. In this...
For the implementation of cellulosic ethanol technology, the maximum use of lignocellulosic materials is important to increase efficiency and to reduce costs. In this context, appropriate use of the pentose released by hemicellulose hydrolysis could improve de economic viability of this process. Since the Saccharomyces cerevisiae is unable to ferment the pentose, the search for pentose-fermenting microorganisms could be an alternative. In this work, the isolation of yeast strains from decaying vegetal materials, flowers, fruits and insects and their application for assimilation and alcoholic fermentation of xylose were carried out. From a total of 30 isolated strains, 12 were able to assimilate 30gL of xylose in 120h. The strain Candida tropicalis S4 produced 6gL of ethanol from 56gL of xylose, while the strain C. tropicalis E2 produced 22gL of xylitol. The strains Candida oleophila G10.1 and Metschnikowia koreensis G18 consumed significant amount of xylose in aerobic cultivation releasing non-identified metabolites. The different materials in environment were source for pentose-assimilating yeast with variable metabolic profile.
Topics: Ethanol; Fermentation; Pentoses; Vegetables; Xylitol; Xylose; Yeasts
PubMed: 28888830
DOI: 10.1016/j.bjm.2016.11.014 -
The American Journal of Clinical... Jan 1992D-Glucosamine (GlcN), N-acetyl-D-glucosamine (GlcNAc) and 2,5-anhydro-D-mannitol (2,5-AM) were infused into the rat third cerebroventricle (icv) to compare their effects... (Review)
Review
D-Glucosamine (GlcN), N-acetyl-D-glucosamine (GlcNAc) and 2,5-anhydro-D-mannitol (2,5-AM) were infused into the rat third cerebroventricle (icv) to compare their effects on food intake. GlcN (24 mumols/L) accelerated eating, and concomitantly increased plasma glucose, free fatty acids, and glycerol without affecting plasma insulin. GlcN accelerated lateral hypothalamic (LHA), and reciprocally decreased ventromedial hypothalamic (VMH) neuronal activity. Infusion of 12 mumols GlcNAc icv did not affect feeding, but oral administration (1200 mumols/L) induced feeding. The GlcNAc-induced feeding was completely abolished by bilateral truncal vagotomy. Infusion of 2,5-AM dose-dependently induced feeding (P less than 0.01). A maximal dose (24 mumols/L) did not substantially change plasma glucose or insulin. Unilateral 2,5-AM microinfusion (1.2 mumols/L) into the VMH, but not into the LHA, elicited feeding. The characteristic actions of these analogues are useful to clarify central control of food intake and also as probes to examine relations between feeding modulation and energy metabolism in the central nervous system.
Topics: Acetylglucosamine; Animals; Eating; Glucosamine; Hexoses; Mannitol; Pentoses
PubMed: 1728839
DOI: 10.1093/ajcn/55.1.272s -
Applied Microbiology and Biotechnology Sep 2018Pentoses represent monosaccharides with five carbon atoms. They are organized into two main groups, aldopentoses and ketopentoses. There are eight aldopentoses and four... (Review)
Review
Pentoses represent monosaccharides with five carbon atoms. They are organized into two main groups, aldopentoses and ketopentoses. There are eight aldopentoses and four ketopentoses and each ketopentose corresponds to two aldopentoses. Only D-xylose, D-ribose, and L-arabinose are natural sugars, but others belong to rare sugars that occur in very small quantities in nature. Recently, rare pentoses attract much attention because of their great potentials for commercial applications, especially as precursors of many important medical drugs. Pentoses Izumoring strategy provides a complete enzymatic approach to link all pentoses using four types of enzymes, including ketose 3-epimerases, aldose-ketose isomerases, polyol dehydrogenases, and aldose reductases. At least 10 types of epimerases and isomerases have been used for biotransformation of all aldopentoses and ketopentoses, and these enzymes are reviewed in detail in this article.
Topics: Aldose-Ketose Isomerases; Biotransformation; Isomerases; Pentoses; Racemases and Epimerases
PubMed: 29968034
DOI: 10.1007/s00253-018-9150-y -
The Journal of Biological Chemistry Apr 1958
Topics: Aldehyde-Lyases; Fermentation; Humans; Lactobacillus; Lactobacillus plantarum; Pentosephosphates; Pentoses; Phosphates; Phosphorylases; Xylulose
PubMed: 13539033
DOI: No ID Found