THE BACTERIAL OXIDATION OF TRYPTOPHAN III

Abstract

Cell-free extracts capable of oxidizing L-tryptophan to beta-ketoadipic acid were obtained by grinding tryptophan-adapted cells of pseudomonads with alumina. With such extracts tryptophan undergoes an initial peroxidation to yield formylkynurenine. Formylkynurenine is in turn hydrolyzed to yield kynurenine, which then undergoes a nonoxidative decomposition to anthranilic acid and alanine. Anthranilic acid is further oxidized via catechol to cis-cis-muconic acid, and this compound is converted in a nonoxidative reaction to beta-ketoadipic acid. Certain properties of the enzymes responsible for this sequence of reactions are described. Extracts prepd. in identical fashion from cells not adapted to tryptophan (grown with asparagine as C source) do not contain detectable amts. of the enzymes necessary for the dissimilation of tryptophan, kynurenine, and catechol, a fact which demonstrates that adaptation to metabolize trytophan involves an actual synthesis by the cell of the relevant enzyme systems.