Alteration of leucine aminopeptidase from Streptomyces septatus TH-2 to phenylalanine aminopeptidase by site-directed mutagenesis.

ABSTRACT: To tailor leucine aminopeptidase from Streptomyces septatus TH-2 (SSAP) to become a convenient biocatalyst, we are interested in Phe221 of SSAP, which is thought to interact with the side chain of the N-terminal residue of the substrate. By using saturation mutagenesis, the feasibility of altering the performance of SSAP was evaluated. The hydrolytic activities of 19 mutants were investigated using aminoacyl p-nitroanilide (pNA) derivatives as substrates. Replacement of Phe221 resulted in changes in the activities of all the mutants. Three of these mutants, F221G, F221A, and F221S, specifically hydrolyzed L-Phe-pNA, and F221I SSAP exhibited hydrolytic activity with L-Leu-pNA exceeding that of the wild type. Although the hydrolytic activities with peptide substrates decreased, the hydrolyti

SUBMITTER: Arima J 

PROVIDER: S-EPMC1287679 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature