Substrate specificity in hydrolysis and transglucosylation by family 1 β-glucosidases from cassava and Thai rosewood
摘要:
Thai rosewood (Dalbergia cochinchinensis Pierre) dalcochinase and cassava (Manihot esculenta Crantz) linamarase are glycoside hydrolase family 1 beta-glucosidases with 47% amino acid sequence identity. Each enzyme can hydrolyze its natural substrate, dalcochinin-8'-O-beta-D-glucoside and linamarin, respectively, but not the natural substrate of the other enzyme. Linamarase can transfer glucose to primary, secondary and tertiary alcohols with high efficiency, while dalcochinase can transglucosylate primary and secondary alcohols at moderate levels. In this study, eight amino acid residues in the aglycone binding pocket of dalcochinase were individually replaced with the corresponding residues of linamarase, in order to identify residues that may account for their catalytic differences. The residues 1185 and V255 of dalcochinase appeared important for its substrate specificity, with their respective mutations resulting in 24- and 12-fold reductions in K-cat/K-m for the hydrolysis of dalcochinin-8'-O-beta-D-glucoside. Transglucosylation activity was improved when 1185, N189 and V255 of dalcochinase were replaced with A201, F205 and F271 of linamarase, respectively, suggesting these residues support transglucosylation in linamarase. Among these three mutants, only the N189F mutant showed significant increases in the rate constants for the reactivation of trapped glucosyl-enzyme intermediates by all alcohols. Together, our results suggest that both hydrophobicity and geometry are important determinants for substrate specificity in hydrolysis and transglucosylation by these family 1 beta-glucosidases. (C) 2010 Elsevier B.V. All rights reserved.
A highly selective enzyme-catalysed esterification of simple glucosides
作者:Fredrik Björkling、Sven Erik Godtfredsen、Ole Kirk
DOI:10.1039/c39890000934
日期:——
Regioselective 6-O-esterification of alkyl glucosides with long chain fatty acids, yielding more than 95% of 6-O-monoesters, can be achieved using lipases as catalysts in a solvent-free process.
induction as phase-transfercatalysts in a few two-phase reactions. The catalytic effect of the lariat ethers with methoxy, ethoxy, and i-propoxy substituents on C-1 of the sugar unit in both α and β positions was compared. In liquid–liquid two-phase reactions, the nature and position of the substituents did not have much effect. The α-anomers were somewhat more efficient in terms of enantioselectivity than
Monoesters of glycosides and a process for enzymatic preparation thereof
申请人:Novo Nordisk A/S
公开号:US05191071A1
公开(公告)日:1993-03-02
Compounds of the formula (R-COO).sub.n X-OR.sup.1, wherein R.sup.1 is optionally substituted alkyl, phenyl, or alkyl phenyl, n is 1, 2 or 3, X is a carbohydrate moiety, and R is optionally substituted alkyl, have superior effects as additives in detergents. These compounds can be prepared by esterification of glycosides using specific enzymes.
Fluorine-containing compounds and polymers derived therefrom
申请人:——
公开号:US20030109626A1
公开(公告)日:2003-06-12
Provided are fluorine-containing compounds, and polymers derived therefrom, for use in compositions used for treating textile substrates. Also provided are methods of making fluorine-containing compounds and polymers derived therefrom, compositions comprising the compounds and/or polymers of the present invention, methods of treating substrates, and the treated products derived therefrom.
Organo glycoside ethers are prepared by reacting saccharide containing compositions with alcohols of 3 or more carbon atoms in the presence of 2 or more moles of water for each aldose unit mole. The method is particularly effective for converting polysaccharides, such as starches to alkyl glycosides by means of a reaction media comprised of starch, an alkanol of at least 3 carbon atoms and at least one other alcohol-soluble organo co-solvent in the presence of an acid catalyst at elevated temperatures under pressure.