Studies on a Carboxypeptidase Y Mutant of Yeast and Evidence for a Second Carboxypeptidase Activity

Abstract

Immunological studies on the carboxypeptidase Y mutant prc1‐1 of Saccharomyces cerevisiae revealed the origin of mutation in the structural gene of carboxypeptidase Y. The absence of carboxypeptidase Y has no effect on growth, even after drastic changes of growth conditions. A double mutant (prc1−leu2−) lacking carboxypeptidase Y and auxotrophic for leucine is able to grow on the peptide benzyloxycarbonylglycylleucine (Cbz‐Gly‐Leu) as sole nitrogen source, indicating the existence of a second carboxypeptidase. Using a new peptidase test, the existence of this second enzyme, called carboxypeptidase S, was confirmed biochemically. Copyright © 1977, Wiley Blackwell. All rights reserved