NOVEL SERINE PENICILLOCARBOXYPEPTIDASE CPD-S3 FROM PENICILLIUM-JANTHINELLUM IBT-3991 - PURIFICATION, CHARACTERIZATION, AND USES IN PEPTIDE-SYNTHESIS AND MODIFICATION

A novel carboxypeptidase (CPD-S3) from Penicillium janthinellum IBT 39 91 has been isolated in a two-step purification procedure by cation ex change and affinity chromatography. The enzyme is a serine carboxypept idase with a denatured molecular mass determined by SDS of 62 kDa of w hich 32% is carbohydrate. The isoelectric point is 5. 1. CPD-S3 exhibi ts a high stability towards organic solvents and elevated temperatures . Besides the carboxypeptidase activity, CPD-S3 exhibits esterase, ami dase, and carboxamidohydrolase activities. CPD-S3 favors substrates Of L-configuration with basic amino acid residues in either P1 or P1', a nd particularly dibasic substrates and medium-sized straight-chain alk yl esters for hydrolysis. In aminolysis of esters, amino acid amides a nd hydrazines coupled in good yield, but methyl esters poorly, and unl ike other carboxypeptidases, free amino acids could not be coupled or transpeptidation effected to form amides. In ester semisynthesis, pept ides with neutral, but not basic, residues in P1 could be esterified. The scope of applicability for enzymatic peptide synthesis is limited.