Expanded structural and stereospecificity in peptide synthesis with chemically modified mutants of subtilisin

Abstract

Employing the strategy of combined site directed mutagenesis and chemical modification, we previously generated chemically modified mutant enzymes (CMMs) of subtilisin Bacillus lentus (SBL). We now report the use of these SBL-CMMs for peptide coupling reactions. The SBL-CMMs exhibit dramatically altered substrate specificity, including the acceptance of d-amino acid acyl donors, generating dipeptides containing d-Phe, d-Ala and d-Glu in up to 66% yield, which was not possible using wild-type SBL (WT-SBL). In addition, SBL-CMMs accommodate α-branched amino acids such as l-Ala-NH 2 as acyl acceptors in their S 1′ pockets, which WT-SBL will not.