Intracellular Peptide Hydrolysis by Pseudomonas putida and Pseudomonas maltophilia

Open Access
Publisher Website
Google Scholar
Abstract
Amino acids liberated by peptidase hydrolysis of di- and oligopeptides by P. putida were measured by trinitrobenzenesulfonate assay and high voltage electrophoresis or paper chromatography followed by ninhydrin spray. Intact bacteria or periplasmic contents released by lysozyme treatment did not hydrolyze peptides. Subcellular fractionation showed that glycylmethionine peptidase activity was cytoplasmic. This enzyme had a Km of 2 mM, and was stimulated 5-fold by 1 mM CO2+. Crude peptidase extract did not cleave peptides with D-residues, acylated N-terminal amino groups or N-methylated peptide bonds but otherwise showed a wide specificity. Di- or tripeptides with blocked C-terminus were hydrolyzed. Leucylleucine (12 mM) and leucylglycylglycine (10 mM) did not compete with glycylmethionine (1.2 mM) and glycylmethionylglycine (1.0 mM), respectively, for hydrolysis. P.maltophilia also contained peptidase activity (0.84 .mu.mol amino acid released from glycylmethionylglycine/min per mg protein). Peptidases of both P. putida and P. maltophilia were constitutive.