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.

Electrochemical characterization of the pyranose 2-oxidase variant N593C shows a complete loss of the oxidase function with full preservation of substrate (dehydrogenase) activity

Abstract: This study presents the first electrochemical characterization of the pyranose oxidase (POx) variant N593C (herein called POx-C), which is considered a promising candidate for future glucose-sensing applications The resulting cyclic voltammograms obtained in the presence of various concentrations of glucose and mediator (1,4-benzoquinone, BQ), as well as the control experiments by addition of catalase, support the conclusion of a complete suppression of the oxidase function and oxygen reactivity at POx-C Additionally, these electrochemical experiments demonstrate, contrary to previous biochemical studies, that POx-C has a fully retained enzymatic activity towards glucose POx-C was immobilized on a special screen-printed electrode (SPE) based on carbon ink and grafted with gold-nanoparticles (GNP) Suppression of the oxygen reactivity at N593C-POx variant is a prerequisite for utilizing POx in electrochemical applications for glucose sensing To our knowledge, this is the first report presented in the literature showing an absolute conversion of an oxidase into a fully active equivalent dehydrogenase via a single residue exchange

A chemoenzymatic synthesis of deoxy sugar esters involving stereoselective acetylation of hemiacetals catalyzed by CALB

Abstract: An extension of the scope of the chemoenzymatic strategy for the synthesis of stereochemically pure pyranose deoxy sugar esters of different carboxylic acids has been achieved. The objective of the work was to extend the strategy to the synthesis of furanose deoxy sugar derivatives and additionally, to N-Boc-protected amino acid esters. With all used carboxylic acids (deoxycholic acid, α-methoxyphenylacetic acid, N-Boc- l -phenylalanine and N-Boc- l -tyrosine) the lipase-catalyzed stereoselective acetylation of furanose or pyranose hemiacetal moiety as a key step afforded one desired stereochemically pure acetylated hemiacetal deoxy sugar ester in high de.

Crystal and molecular structure of a carbohydrate-derived oxetan-3-one. Definitive evidence for a novel participation of a pyranose ring oxygen atom

Abstract: The crystal and molecular structure of (1S)-5,7-anhydro-8-deoxy-1,2 :3,4-di-O-isopropylidene-1-O-methyl-D-glycero-D-galacto-octos-6-ulose has been determined by X-ray analysis. It crystallizes in the tetragonal P41(P43) space group, with a=b= 10.239(5), c= 16.369(7)A, Z= 4. The structure was solved by direct methods and refined to an R value of 5.3%. The octose chain is bent in such a way as to keep C-2, -3, -4, and -5 in the same plane. The formation of this compound during the methanolysis of 7,8-dideoxy-7-diazo-1,2 :3,4-di-O-isopropylidene-α-D-galacto-octos-6-ulopyranose(3) by participation of the pyranose ring oxygen atom is discussed in the light of current ideas on diazo-ketone substitution.

Polarizing plate and liquid crystal display device

Abstract: A polarizing plate (3) in which the total thickness of a first protective film (11), a polarizing film (12), and a second protective film (13) is 90 [mu]m or less The moisture permeability of the first protective film (11) is equal to or less than 400 g/m224 hr The second protective film (13) contains a cellulose ester and a retardation-lowering agent The retardation-lowering agent contains a sugar ester obtained by esterifying, using an aliphatic acyl group, all or some of the OH groups in a compound (A) having a furanose structure or a pyranose structure or a compound (B) in which two to twelve furanose structures and/or pyranose structures are bonded together The second protective film (13) has an Ro of 0 to 10 nm and an Rt of -10 to +10 nm

Electrospray ionization mass spectrometric analysis of newly synthesized α,β-unsaturated γ-lactones fused to sugars

Abstract: Knowledge of the fragmentation mechanisms of lactones and their behaviour under electrospray ionization (ESI) conditions can be extended to larger and more complex natural products that contain an alpha,beta-unsaturated gamma-lactone moiety in their structure. Moreover, little is known about the gas-phase behaviour of alpha,beta-unsaturated gamma-lactones linked or fused to sugars. Therefore, five alpha,beta-unsaturated gamma-lactones (butenolides) fused to a pyranose ring, recently synthesized compounds with potential relevance regarding their biological properties, were investigated using ESI-MS and ESI-MS/MS in both positive and negative ion modes. Their fragmentation mechanisms and product ion structures were compared. It was observed that two isomers could be unambiguously distinguished in the negative ion mode by the fragmentation pathways of their deprotonated molecules as well as in the positive ion mode by the fragmentation pathways of either the protonated or the sodiated molecule. Fragmentation mechanisms are proposed taking into account the MS/MS data and semi-empirical calculations using the PM6 Hamiltonean. The semi-empirical calculations were also very useful in determining the most probable protonation and cationization sites.