Cloning, screening and characterization of enantioselective ester hydrolases from Escherichia coli K-12

Thirty-one ester hydrolases were cloned from Escherichia coli K-12 and an efficient screening strategy was applied to screen and characterize them, emphasizing on their enantioselectivity. We are the first to investigate the enantioselectivity of these enzymes, although their activity had been reported by other researchers. The enzyme XL3 from gene b0349, XL10 from gene b0494, XL15 from gene b3412, XL27 from gene b2154 and XL31 from gene b3825 exhibited high activity towards p -nitrophenyl esters with short chain. The enzyme XL15 from gene b3412 was demonstrated for the first time to show high enantioselectivity to ( R )-1-phenylethyl acetate both in hydrolysis and esterification with enantioselectivity value ( E)  > 100 at the conversion of 31.2 and 36.8%, respectively.