Preparation of optically pure tert-leucine by penicillin G acylase-catalyzed resolution

Penicillin G acylase, from Kluyvera citrophila, was used in kinetic resolution of DL-tert-leucine. N-phenylacetylated-DL-tert-leucine, chemically synthesized from DL-tert-leucine, was enantioselctively hydrolyzed by penicillin G acylase to obtain L-tert-leucine, D-tert-leucine was prepared by acid-catalyzed hydrolysis of the remaining substrate. The total yields of D-tert-leucine and L-tert-leucine are 80.6% and 83.1%, respectively. The enantiomeric excess of the two products, D-tert-leucine and L-tert-leucine, are 98.5% and 99%. This is a practical way for the preparation of D-tert-leucine and L-tert-leucine.