| Résumé | Aspergillus amstelodami PRL 1698 synthesized echinulin when it was grown on molasses medium to which was added cyclo-L-alanyl-L-tryptophyl (both labeled with ¹⁴C in the methylene carbon of the tryptophyl moiety.) The organism incorporated radioactivity from cyclo-L-alanyl-L-tryptophyl-¹⁴C into echinulin in a specific way, and to a greater extent than from cyclo-L-alanyl-D-tryptophyl-¹⁴C. There was greater incorporation of radioactivity from cyclo-L-alanyl-L-tryptophyl-¹⁴C into echinulin than into mycelial tryptophan, and the incorporation into echinulin was not significantly lessened by adding unlabeled trytophan to the medium. therefore, cyclo-L-alanyl-L-tryptophyl-¹⁴C was not hydrolyzed to tryptophan-¹⁴C before incorporation of radioactivity into echinulin, and the cyclic dipeptide itself appears to be an intermediate in the biosynthesis of echinulin |
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