EFFECTS OF α-METHYL-DL-TRYPTOPHAN ON THE OXIDATION OF TRYPTOPHAN

Abstract

α-Methyl-DL-tryptophan (AMT) inhibits the oxidation of DL-tryptophan by isotonic suspensions of rat liver, and the oxidation of L-tryptophan, L-tyrosine, DL-phenylalanine, and DL-methionine by cobra venom. The oxidation of L-tryptophan is accompanied by the appearance of a yellow color in the reaction mixtures. AMT also inhibits the formation of kynurenine, detected by its specific absorption at 360 mμ and by diazotization, from L-tryptophan. It protects the kynurenine-forming enzyme system against the inactivation which occurs in the absence of substrate. When injected into the rat, AMT, like tryptophan, causes an adaptive increase in the tryptophan peroxidase–oxidase complex. AMT is not oxidized by the liver and venom preparations used.