Relations between tryptophan configuration and actinomycin biosynthesis

Addition of D‐tryptophan to the growth media of Streptomyces V‐187 results in an inhibition of actinomycin production, while growth of the microorganism appears to be unaffected. L‐tryptophan overcomes the inhibition brought about by the D‐stereoisomer. D‐[benzene ring‐14C]‐tryptophan is taken up by the cells of Streptomyces V‐187 and incorporated into proteins and actinomycin almost to the same extent of L‐[benzene ring‐14C]‐tryptophan, though at a slower rate. The benzene ring of both stereoisomers contributes only to the phenoxazinone residue of the actinomycin molecule. Indeed, D, L‐[methylene‐14C]‐tryptophan is incorporated into actinomycin only to a very small extent. Other possible precursors of the chromophoric residue of actinomycin, [benzene ring‐14C]‐indolepyruvic acid, [benzene ring‐14C]‐benzoic acid and [uniformly‐14C]‐shikimic acid, were not taken up by the cells in significant amounts.