Enzvmatic Formation of Catechol from Anthranilic Acid*

Anthranilic acid is known to be formed from kynurenine in animals and microorganisms (3-6) and to be degraded by cell-free extracts of a Pseudomonas species adapted to L-tryptophan (7). Catechol has been postulated as an intermediate in the catabolism of anthranilic acid on the basis of experiments utilizing sequential enzyme induction (8). Several groups of investigators have recently succeeded in partially purifying and characterizing the enzyme responsible for the oxidation of anthranilic acid (g-12), but because of the instability of the enzyme and the complex nature of the reaction, properties of the enzyme and the reaction mechanism still remain obscure. Furthermore, the role of catechol in the catabolism of anthranilic acid has not been established, since these enzyme preparations invariably contained significant levels of pyrocatechase. Direct evidence for the formation of catechol from anthranilic acid is necessary to provide a firmer basis for further studies on the mechanism of anthranilic acid oxidation. In the work presented, catechol has been identified as an intermediate in the degradation of anthranilic acid by a Pseudomonas species. In addition, the mechanism of this transformation is investigated in connection with the enzymatic hydroxylation of the aromatic ring at 2 adjacent carbon atoms (13, 14).