Topic
Aldose
About: Aldose is a research topic. Over the lifetime, 1270 publications have been published within this topic receiving 27197 citations. The topic is also known as: aldoses.
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TL;DR: In this article, the 2-ketohexoses d -fructose, l -sorbose, and d -tagatose undergo a stereospecific intramolecular rearrangement to give the corresponding 2-C-(hydroxymethyl)aldoses.
29 citations
TL;DR: The physiological role of quinoprotein aldose dehydrogenase in this organism may be primarily in energy generation, since the enzyme has no function in carbon metabolism, except perhaps in strains growing on pentoses at high pH.
Abstract: The ratios of the oxidation rates of aldose sugars, determined in cell-free extracts of Acinetobacter calcoaceticus, vary with the strain and growth conditions used. Three distinct forms of glucose dehydrogenase with different substrate specificities, occurring in variable proportions in these extracts, are responsible for this effect. One form is the already known “soluble glucose dehydrogenase”, the other two forms are complexes containing enzyme and components of the respiratory chain. The proportions in which the enzyme forms are found in the cell-free extract correlate with the oxidative behaviour of whole cells with respect to aldose sugars. It is concluded, therefore, that the enzyme forms are not an artefact of the isolation procedure but that they exist as such in vivo. Since the two complexes can be converted into the soluble enzyme form, aldose dehydrogenase can, probably, be integrated in three different ways into the respiratory chain. The presence of glucose during growth does not stimulate aldose dehydrogenase production. This is not surprising since the enzyme has no function in carbon metabolism, except perhaps in strains growing on pentoses at high pH. Therefore, the physiological role of quinoprotein aldose dehydrogenase in this organism may be primarily in energy generation.
29 citations
TL;DR: It is shown by NMR that hydrogen exchange between substrate and solvent occurs during the reaction catalysed by PfPGI eliminating the possibility of a hydride-shift-based mechanism and 5-phospho-d-arabinonohydroxamate, a stable analogue of the putative cis-enediol intermediate, is the most potent inhibitor of the enzyme yet discovered.
29 citations
TL;DR: In this paper, high functionalized and densely oxygenated bicyclic compounds were obtained by treating a modified carbohydrate template with SmI 2 and a ketone or aldehyde which effected a tandem radical cyclization and carbonyl addition reaction.
29 citations
TL;DR: The structure of this complex supports the hypothesis that an imidazole group catalyzes ring opening of the pyranose, and a stereochemically sensible model is produced which is consistent with other data.
Abstract: Crystal structures of complexes of D-xylose isomerase with deoxysugars have been determined. Deoxynojirimycin is a structural analogue of alpha-pyranose and mimics the binding of these aldose substrates. The structure of this complex supports the hypothesis that an imidazole group catalyzes ring opening of the pyranose. The steric restrictions in the active site of the enzyme prevent a beta-pyranose from binding in the same way. For the reverse reaction with ketoses, the anomeric specificity is less certain. Dideoxyimino-D-glucitol is a structural analogue of the ketose alpha-D-furanose. The binding of the inhibitor dideoxyimino-D-glucitol to the crystals of the enzyme does not mimic the binding of the reactive alpha-D-fructofuranose. Superposition of the nonphysiological substrate alpha-D-fructofuranose onto the atomic positions of dideoxyimino-D-glucitol is not possible due to the steric restrictions of the active site. However, by utilizing the approximate 2-fold symmetry of the sugar, a stereochemically sensible model is produced which is consistent with other data. In addition to reaction with alpha-D-furanose, the enzyme probably reacts with open ring keto sugars which are present at significant concentrations. Other sugars which resemble furanoses either do not inhibit significantly or are not observed in the crystals bound in a single conformation.
29 citations