ROLE OF AMINOTRANSFERASE AND INDOLE-3-PYRUVIC ACID IN THE SYNTHESIS OF INDOLE-3-ACETIC ACID IN PSEUDOMONAS SAVASTANOI

Abstract

An aminotransferase with broad specificity was partially purified from Pseudomonas savastanoi. The enzyme catalyzes the conversion of L-tryptophan to indole-3-pyruvic acid (IPYA) but transaminates more readily with other amino acids. Optimal activity occurs at pH 8.8. The aminotransferase shows broad specificity for both amino donors and acceptors. Indole- 3-acetic acid (IAA) and indole-3-acetamide (IAM) at 3×10^-3M inhibit minotransferase activity 30% and 26%, respectively. Specific activity of aminotransferase from cells grown in a medium with L-tryptophan or IAA does not appear to affect production of the enzyme. Whole cells of Pseudomonas savastanoi convert IPYA to IAA but the overall conversion is slower than the rate of conversion of IAM to IAA. The role of aminotransferase in the synthesis of IAA from tryptophan is considered to be minor to that of the oxidative decarboxylase-hydrolase system in this bacterium.