Directed Evolution of an Enantioselective Lipase with Broad Substrate Scope for Hydrolysis of α-Substituted Esters

A variant of Candida antarctica lipase A (CalA) was developed for the hydrolysis of a-substituted p-nitrophenyl esters by directed evolution. The E values of this variant for 7 different esters was 45-276, which is a large improvement compared to 2-20 for the wild type. The broad substrate scope of this enzyme variant is of synthetic use, and hydrolysis of the tested substrates proceeded with an enantiomeric excess between 95-99%. A 30-fold increase in activity was also observed for most substrates. The developed enzyme variant shows (R)-selectivity, which is reversed compared to the wild type that is (S)-selective for most substrates.