Application of directed evolution in the development of enantioselective enzymes

A novel approach to developing enantioselective enzymes for use in organic chemistry has been devised which is independent of structural or mechanisti c aspects. The underlying idea is to combine appropriate methods of random mutagenesis, gene expression, and high-throughput screening for enantiosele ctivity. If these actions are performed in repetitive cycles, an evolutiona ry pressure is created that leads to sequential improvements of the enantio selectivity of a given enzyme-catalyzed reaction. The concept is illustrate d by an example involving the lipase-catalyzed hydrolytic kinetic resolutio n of an a-chiral ester, the enantioselectivity increasing from ee = 2% (E = 1.1) for a wild-type enzyme to cc = 90-93% (E = 25) for the best mutants.