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

作者：Frutuoso M A; Marana S R^*

来源：Protein and Peptide Letters, 2013, 20(1): 102-106.

DOI：10.2174/092986613804096757

• beta-glucosidases
• glycoside hydrolases
• oligosaccharides synthesis
• Spodoptera frugiperda
• Tenebrio molitor
• transglycosylation

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.

• 出版日期2013-1