THE UTILIZATION OF TRYPTOPHAN IN THE BIOSYNTHESIS OF ECHINULIN

Abstract

Aspergillus amstelodami was grown on molasses medium to which was added DL-tryptophan, labeled with 14 C in the 2 position of the indole ring or in the carboxyl, α, or methylene carbons of the alanine side chain. All of these labeled compounds were incorporated by the organism to a significant extent into echinulin. Carboxyl- 14 C-labeled DL-tryptophan was incorporated into echinulin without appreciable randomization of radioactivity. Methylene- 14 C-labeled L-tryptophan was used to a greater extent in the biosynthesis of echinulin than was the D-isomer. Both the D- and L-isomers were used more efficiently in the synthesis of fungal tryptophan than for the synthesis of echinulin.