13299-15-5Relevant articles and documents
Hydrolysis of (2-deoxy-α-D-glucopyranosyl)pyridinium salts: The 2- deoxyglucosyl oxocarbenium is not solvent-equilibrated in water
Zhu, Jiang,Bennet, Andrew J.
, p. 3887 - 3893 (1998)
The hydrolysis reactions of four 2-deoxy-α-D-glucopyranosyl pyridinium salts exhibit first-order rate constants that are independent of pH in the range of 4.4-10.5 pH units. Derived second-order rate constants for the hydrolysis reactions of 2-deoxy-α-D-glucopyranosyl 4'-bromoisoquinolinium tetrafluoroborate (4d) conducted in the presence of nucleophilic monoanions (u = 2.0) including AcO-, Cl-, Br-, and N3/- exhibit a Swain-Scott parameter (s) of 0.03 ± 0.10, indicating that these reactions show no sensitivity to the nature of the anion. In the presence of azide ion, a substantial quantity of the 2-deoxy-α-glucopyranosyl 4'-bromoisoquinolinium salt hydrolysis product results from a post rate-limiting reaction of a cationic intermediate with azide. Analysis of the hydrolysis product ratios indicates that the 2-deoxyglucosyl oxocarbenium ion is not solvent- equilibrated in water. Furthermore, the reaction of solvent occurs about 2- fold faster with the cationic intermediate that is formed during solvolysis of the β-anomeric salt than with the corresponding intermediate produced from the reactions of the α-anomer 4d.
Glycon specificity profiling of α-glucosidases using monodeoxy and mono-O-methyl derivatives of p-nitrophenyl α-D-glucopyranoside
Nishio, Toshiyuki,Hakamata, Wataru,Kimura, Atsuo,Chiba, Seiya,Takatsuki, Akira,Kawachi, Ryu,Oku, Tadatake
, p. 629 - 634 (2007/10/03)
Hydrolysis of probe substrates, eight possible monodeoxy and mono-O-methyl analogs of p-nitrophenyl α-D-glucopyranoside (pNP α-D-Glc), modified at the C-2, C-3, C-4, and C-6 positions, was studied as part of investigations into the glycon specificities of seven α-glucosidases (EC 3.2.1.20) isolated from Saccharomyces cerevisiae, Bacillus stearothermophilus, honeybee (two enzymes), sugar beet, flint corn, and Aspergillus niger. The glucosidases from sugar beet, flint corn, and A. niger were found to hydrolyze the 2-deoxy analogs with substantially higher activities than against pNP α-D-Glc. Moreover, the flint corn and A. niger enzymes showed hydrolyzing activities, although low, for the 3-deoxy analog. The other four α-glucosidases did not exhibit any activities for either the 2- or the 3-deoxy analogs. None of the seven enzymes exhibited any activities toward the 4-deoxy, 6-deoxy, or any of the methoxy analogs. The hydrolysis results, with the deoxy substrate analogs, demonstrated that α-glucosidases having remarkably different glycon specificities exist in nature. Further insight into the hydrolysis of deoxyglycosides was obtained by determining the kinetic parameters (kcat and Km) for the reactions of sugar beet, flint corn, and A. niger enzymes.
Solvolyses of 2-Deoxy-α- and β-D-Glucopyranosyl 4′-Bromoisoquinolinium Tetrafluoroborates
Zhu, Jiang,Bennet, Andrew J.
, p. 4423 - 4430 (2007/10/03)
The solvolyses of 2-deoxy-α- and β-D-glucopyranosyl 4′-bromoisoquinolinium tetrafluoroborates (1 and 2) were monitored in aqueous methanol, ethanol, trifluoroethanol, and binary mixtures of ethanol and trifluoroethanol. The observed rate constants are consistent with the solvolyses of 1 and 2 proceeding via dissociative (DN * AN) transition states. In comparison to the α-anomer, solvolysis of the β-compound gives a greater transition state charge delocalization onto the ring oxygen atom. Analysis of the solvolysis product ratios indicates that the 2-deoxyglucosyl oxacarbenium ion is not solvent-equilibrated in the solvent mixtures studied. In the solvolysis of compound 1, the solvent trifluoroethanol facilitates diffusional separation of the leaving group and, in so doing, promotes the formation of the retained trifluoroethyl glycoside.
