Enantioselective enzymes for organic synthesis created by directed evolution

A new concept for the creation of enzymes displaying improved enantioselect ivity in a given reaction is described; it is based on "evolution in the te st tube". Accordingly, proper molecular biological methods for random mutag enesis,gene expression, and high-throughput screening systems for the rapid assay of enantioselectivity are combined. Several rounds of mutagenesis an d screening are generally necessary in order to create mutant enzymes that show high degrees of enantioselectivity, as in the case of the lipase-catal yzed hydrolytic kinetic resolution of a chiral ester in which the original enantioselectivity of 2 % ee (E = 1) increases to > 90 % ee (E = 25).