A Single Amino Acid Residue Determines the Ratio of Hydrolysis to Transglycosylation Catalyzed by beta-Glucosidases

Author(s)

Frutuoso, M. A. ^[1] ; Marana, S. R. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-05513970 Sao Paulo - Brazil

• Document type: Journal article
• Source: PROTEIN AND PEPTIDE LETTERS; v. 20, n. 1, p. 102-106, JAN 2013.
• Web of Science Citations: 14

Abstract

The propensity to catalysis of transglycosylation of the beta-glucosidase Tm beta gly is higher than for Sf beta gly. Moreover the propensity to catalysis of transglycosylation is directly proportional to the substrate concentration for Tm beta gly, whereas for Sf beta gly it is constant. For instance, 60% of a Tm beta gly sample catalyzes transglycosylation reactions at 40 mM p-nitrophenyl beta-glucoside, whereas only 40% is engaged in hydrolysis of this substrate. For Sf beta gly the fraction involved in transglycosylation is only 30%. In addition, 48% of a Tm beta gly sample catalyzes transglycosylation reactions at 8 mM methylumbelliferyl beta-glucoside, whereas Sf beta gly does not catalyze transglycosylation using this substrate. Interestingly, these Tm beta gly properties were grafted into Sf beta gly by a single replacement of a residue forming a channel involved in supplying the catalytic water molecules for attack on the covalent intermediate present in the reaction catalyzed by beta-glucosidases. Hence a single residue determines the ratio of hydrolysis to transglycosylation reactions catalyzed by these beta-glucosidases. (AU)

• FAPESP's process: 08/55914-9 - Development of beta-glycosidases designed to improve the efficiency of noncomplexed cellulase systems
• Grantee: Sandro Roberto Marana
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants