61-58-5Relevant articles and documents
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.
Glycosidase-catalyzed hydrolysis of 2-deoxyglucopyranosyl pyridinium salts: Effect of the 2-OH group on binding and catalysis
Tanaka, Kelly S. E.,Zhu, Jiang,Huang, Xicai,Lipari, Francesco,Bennet, Andrew J.
, p. 577 - 582 (2007/10/03)
Three 2-deoxy-α-D-glucopyranosyl pyridinium tetrafluoroborates were tested for their binding affinity to a range of α-glucosidases and α-mannosidases. The α- isoquinolinium salt (11) binds approximately 275-fold more tightly to yeast α-glucosidase than does the isomeric quinolinium salt (12). In addition, compound 11 binds to the yeast enzyme approximately two-fold tighter than the corresponding glucopyranosyl isoquinolinium salt (9). The (k(cat)/k(hyd)) values for the yeast α-glucosidase-catalyzed reactions of 11 and 9 are 1.6 x 105 and 2.0 x 109, respectively, when compared to the spontaneous uncatalyzed reactions. Thus, the interaction of the 2-OH group in compound 9 with the yeast enzyme's active site generates a relative transition state stabilization of about 23.5 kJ mol-1. For both compounds 11 and 12, the observed rate accelerations for the yeast α-glucosidase-catalyzed hydrolysis, relative to the spontaneous reaction in solution, (k(cat)/k(hyd) are identical within experimental error.
Hydrolysis of (2-deoxy-β-D-glucopyranosyl)pyridinium salts
Huang, Xicai,Surry, Clint,Hiebert, Timothy,Bennet, Andrew J.
, p. 10614 - 10621 (2007/10/03)
The hydrolysis reactions of three (2-deoxy-β-D-glucopyranosyl)pyridinium salts exhibit first-order rate constants that are independent of pH in the range of 4.4-10.1 pH units. Derived second-order rate constants for the hydrolysis reactions of (2-deoxy-β-D-glucopyranosyl)-4′-bromoisoquinolinium bromide (5b) conducted in the presence of nucleophilic monoanions (μ = 2.0) including AcO-, Cl-, Br-, and N3 exhibit a Swain-Scott parameter (s) of 0,03 ± 0.05, indicating that these reactions show no sensitivity to the nature of the anion. However, a substantial quantity of the (2-deoxyglucopyranosyl)pyridinium salt hydrolysis product is formed as a result of a post-rate-limiting reaction involving a nucleophilic anion. Analysis of the product ratios indicates that the first-formed intermediate in the hydrolytic reaction is a solvent-separated ion painmolecule encounter complex. The data allow a calculated estimate of greater than 2.5 × 10-12 s for the lifetime of the glucopyranosyloxocarbenium ion in aqueous solution.
