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.

Substrate Preference Pattern of Agaricus meleagris Pyranose Dehydrogenase Evaluated through Bioelectrochemical Flow Injection Amperometry

Abstract: Pyranose dehydrogenase (PDH) is a quinone-dependent extracellular flavoglycoprotein mainly produced by litter-decomposing fungi and contributes to the degradation of lignocellulose. PDH in terms of structure and catalytic features pertains to the glucose methanol-choline oxidoreductase family and oxidizes a wide substrate range of aldopyranoses including hexoses, pentoses, disaccharides and oligosaccharides with a high degree of regioselectivity. The purpose of this study was to rationalize the preference of PDH immobilized on an electrode with the structural features of various substrates and thus the kinetic constants were measured for various sugars. PDH was co-immobilized on the electrode with an osmium redox polymer. Response currents for different sugars were measured using flow injection amperometry at +0.3 V vs. Ag|AgCl, KCl (0.1 M). The Michaelis-Menten constants, the turnover numbers and the catalytic efficiency were calculated and revealed that type, orientation and configuration of the substituent play a major role on substrate preference. An OH-group at C-1 and C-6 are not essential and substrate specificities are little affected by the substitution at C-1. The presence and orientation of OH− at C-2 and C-3 are relevant for reactivity. Orientation of OH− at the C-4 position has little effect, and sugars with a substitution below the plane at C-5 are not suitable as substrate. Highest activity for oxidation of glucose, mannose and sucrose was detected at pH 8.5. (Less)

Dynamics of the protein structure of T169S pyranose 2-oxidase in solution: Molecular dynamics simulation.

Abstract: Pyranose 2-oxidase (P2O) from Trametes multicolor contains FAD as cofactor, and forms a tetramer. The protein structure of a mutated P2O, T169S (Thr169 is replaced by Ser), in solution was studied by means of molecular dynamics simulation and analyses of photoinduced electron transfer (ET) from Trp168 to excited isoalloxazine (Iso*), and was compared with wild type (WT) P2O. Hydrogen bonding between Iso and nearby amino acids was very similar as between T169S and WT protein. Distances between Iso and Tyr456 were extremely heterogeneous among the subunits, 1.7 (1.5 in WT) in subunit A (Sub A), 0.97 (2.2 in WT) in Sub B, 1.3 (2.1 in WT) in Sub C, 1.3 nm (2.0 in WT) in Sub D. Mean values of root of mean square fluctuation over all residues were greater by four times than those in WT. This suggests that the protein structure of T169S is much more flexible than that of WT. Electrostatic (ES) energies between Iso anion in one subunit and ionic groups in the entire protein were evaluated. It was found that more than 50% of the total ES energy in each subunit is contributed from other subunits. Reported fluorescence decays were analyzed by a method as WT, previously reported. Electron affinities of Iso* in T169S were appreciably higher than those in WT. Static dielectric constants near Iso and Trp168 were also quite higher in T169S than those in WT. This article is protected by copyright. All rights reserved.