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.

Pyranose ring conformations in mono- and oligosaccharides: a combined MD and DFT approach.

Abstract: Among the descriptors of the molecular structure of carbohydrates, the conformation of the pyranose ring is usually the most problematic one to tackle. We present the results of a systematic study oriented at determining the ring-inversion properties of all D-hexopyranoses in the form of monosaccharides, O1-methylated monosaccharides and homotrisaccharides. Contrary to the existing studies, based either on molecular mechanics force fields or on conformational search within ab initio potentials, we combine the structural information from molecular dynamics simulations performed within the GROMOS 56a6CARBO_R force field and use it in a subsequent geometry optimization procedure, performed at the DFT level of theory. This two-step procedure allows avoiding errors resulting from overestimating the contribution of the hydrogen bond-rich, low-energy structures that are not abundant in aqueous solutions. The calculated anomeric ratios and the populations of staggered conformers of the hydroxymethyl group are in satisfactory agreement with the experimental data. Regarding the ring-inversion properties, for the first time, we achieved good agreement of the ab initio-derived data for all hexopyranoses with the experimentally inferred Angyal scheme and with the NMR-inferred populations of ring conformers. The same computational methodology allows determination of the influence of functionalization (methylation or glycosylation) on the ring-inversion properties which includes the influence of the anomeric effect, enhanced upon O1-functionalization. In general, the correlation between ring-inversion properties of unfunctionalized monomers and those of O1-methylated, O1-glycosylated, O4-glycosylated and O1,O4-diglycosylated monomers is qualitatively (but not quantitatively) compatible with that predicted by the classical force fields.

Characterization of a bacterial pyranose 2-oxidase from Arthrobacter siccitolerans

Abstract: In this study we provide the first biochemical characterization of a bacterial pyranose 2-oxidase (AsP2Ox) from Arthrobacter siccitolerans. The enzyme catalyzes the oxidation of several aldopyranoses at the C-2 position, coupling it to the reduction of dioxygen to hydrogen peroxide. Pyranose 2-oxidases belong to the glucose-methanol-choline oxidoreductase family. A structural model based on the known X-ray structure of P2Ox from Phanerochaete chrysosporium supports that AsP2Ox shares structural features with well-characterized fungal P2Oxs. The gene coding for AsP2Ox was cloned and heterologously expressed in Escherichia coli. The purified recombinant enzyme is a 64-kDa monomer containing a non-covalently bound flavin adenine dinucleotide (FAD) cofactor, distinct features as compared with fungal counterparts that are ∼ 270 kDa homotetramers with covalent-linked FAD. AsP2Ox exhibits a redox potential of −50 mV, an optimum temperature of 37 °C and an optimum pH at 6.5. AsP2Ox oxidizes d -glucose at the highest efficiency, using additionally d -galactose, d -xylose, l -arabinose and d -ribose as electron donors, coupling their oxidation to the reduction of both dioxygen and 1,4-benzoquinone. AsP2Ox shows a relatively low thermal stability with a melting temperature (Tm) of 43 °C and a half-life (t1/2) at 40 °C of 25 min. This work expands the repertoire of bacterial oxidoreductases with importance in biotechnological and diagnostic applications.

Optical film, polarizing plate and liquid crystal display apparatus

Abstract: Disclosed is an optical film having a hard coat layer on a cellulose ester film, which contains an ester compound composed of a furanose structure or a pyranose structures and a sum of a number of the furanose structures or the pyranose structure is 1 to 12, provided that a part of hydroxy groups of the furanose structure or the pyranose structure has been esterified and a part of hydroxy groups of the furanose structure or the pyranose structure remains.

[116a] Periodate oxidation of ribonucleic acids and their derivatives

Abstract: Publisher Summary This chapter discusses the periodate oxidation of RNAs and their derivatives. When ribonucleosides or ribonueleotides are incubated with excess periodate at room temperature near neutrality during short reaction periods (up to 3 hours), the oxidation is practically specific for the glycol groups of the ribosyl components. The number of the glycol groups is obviously determined by the ring (furanose or pyranose) structure of the ribose groups and the position of the phosphoryl groups. Under the reaction conditions defined above, the amounts of periodate consumed can be considered as an accurate measure of the number of glycolic hydroxy groups of the ribose groups, whereas the nitrogenous rings are not affected. The products of the periodate oxidation of natural (ribofuranosyl) ribonucleosides and 5'-ribonucleotides are the corresponding 2′,3′-dialdehyde compounds. Neither formaldehyde nor formic acid is formed. As would be anticipated on the basis of the cis configuration of the 2′- and 3′-OH groups in ribose, the periodate oxidation proceeds rapidly to completion. The chapter also discusses the influence of periodate oxidation on the stability of the phosphoric ester linkage and the purine- and pyrimidine-ribosyl linkages of 5′-nucleotides.