Topic
Pyranose
About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.
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TL;DR: It is shown that the complete free energy of puckering is required to evaluate the accuracy of semiempirical methods used to study reactions involving carbohydrates, and it is found that reducing the free energy space to lower dimensions results in near meaningless minimum energy pathways.
Abstract: The puckered conformations of furanose and pyranose carbohydrate rings are central to analyzing the action of enzymes on carbohydrates. Enzyme reaction mechanisms are generally inaccessible to experiments and so have become the focus of QM(semiempirical)/MM simulations. We show that the complete free energy of puckering is required to evaluate the accuracy of semiempirical methods used to study reactions involving carbohydrates. Interestingly, we find that reducing the free energy space to lower dimensions results in near meaningless minimum energy pathways. We analyze the furanose and pyranose free energy pucker surfaces and volumes using AM1, PM3, PM3CARB-1, and SCC-DFTB. A comparison with DFT optimized structures and a HF free energy surface reveals that SCC-DFTB provides the best semiempirical description of five- and six-membered carbohydrate ring deformation.
79 citations
TL;DR: In this article, magnetic resonance properties of hydroxyl protons are described for a variety of sugars and derivatives in dimethyl sulfoxide, particularly for differentiating between certain types of interconvertible molecular species.
Abstract: Some magnetic resonance properties of hydroxyl protons are described for a variety of sugars and derivatives in dimethyl sulfoxide. Spectral information of this kind is shown to be useful, particularly for differentiating between certain types of interconvertible molecular species. For example, a reducing sugar may be characterized as pyranose or furanose depending upon whether it exhibits a resonance signal that can be ascribed to OH-4 or OH-5, respectively. According to the data obtained, α-D-glucose, α-D-xylose, β-D-arabinose, α-D-lyxose, and α- and β-D-ribose are pyranoses when freshly dissolved, whereas the 2,3-carbonate of D-mannose or D-lyxose is in a furanose form. Selective deuteration and spin decoupling were of primary importance in making some of the spectral assignments.Although arabinose, ribose, and galactose exist partly as furanoses in mutarotated aqueous solutions, their tendency to adopt the structure of the five-membered ring is much greater in dimethyl sulfoxide. Such variability may ...
77 citations
TL;DR: The determination of the structure of this protein provides fundamental knowledge for understanding its mode of action and the nature of allosteric conformational changes that regulate its function.
77 citations
TL;DR: It was verified that the pyranose ring exists in the 1C (1-C4) conformation as the alph-D anomer and no mutarotation was detectable and coupling constants for the glycerol side chain were interpreted to yield its most likely conformation.
76 citations
TL;DR: In this article, a copper-catalysed hydrogenation mechanism was proposed for the boric esters of d -mannitol and the diastereoselectivity of the hydrogenation of seven other ketoses.
76 citations