Directed evolution and axial chirality:: optimization of the enantioselectivity of Pseudomonas aeruginosa lipase towards the kinetic resolution of a racemic allene

Directed evolution of Pseudomonas aeruginosa lipase by the use of combinatorial active site saturation test ( CAST) criteria provided a highly enantioselective mutant (Leu162Phe) for kinetic resolution of an axially chiral allene, p-nitrophenyl 4-cyclohexyl-2-methylbuta-2,3-dienoate ( E = 111); the high enantioselectivity of the Leu162Phe mutant was rationalized by pi - pi stacking.