Process Biochemistry, Vol.45, No.4, 475-480, 2010
Cloning, screening and characterization of ester hydrolases with enantioselectivity in typical bacteria
A broad exploitation of ester hydrolases from 7 typical bacteria was reported in this study. Thirty-two predicted esterases and hydrolases were cloned based on published genomic information. The catalytic activity of obtained clones was tested with p-nitrophenyl esters at various temperatures and pH values. The results indicated that eight enzymes presented with typical esterase activity on p-nitrophenyl butylate and caprylate. The result also showed that despite their great sequence difference, the eight enzymes shared similar properties (substrate specificity, optimal pH and temperature) with each other. Phylogenetic analysis revealed a close relationship between these eight enzymes and "true esterases". As there was no information on enantioselectivity of these enzymes reported, the enantioselectivity of these enzymes to various chiral substrates was investigated for the first time. In comparison with commercial enzyme, Candida rugosa lipase (CRL), enzymes E12, E14, E18, E21 and E24 presented with equal or higher activity and enantioselectivity to the substrates. Furthermore, enzyme E14 (predicted carboxylesterase from Rhodobacter sphaeroides), E21 (S-formylglutathione hydrolase from Pseudomonas putida) and E24 (carboxylesterase from P. putida) presented with enantioselectivity in the resolution of methyl mandelate, 1-phenyethyl acetate and 2-octanol. These findings suggested that the novel ester hydrolases with high activity and enantioselectivity could be obtained from alpha/beta hydrolase family. (C) 2009 Elsevier Ltd. All rights reserved.