Presence of δ-( l -α-Aminoadipyl)- l -Cysteinyl- d -Valine in Fermentations of Penicillium chrysogenum

Cultures ofPenicillium chrysogenum , growth with [35 S]sulfate or labeled amino acids, were examined by ion-exchange chromatography for possible peptidic precursors of penicillin. A sulfur-containing compound, present in both the mycelial extracts and the culture filtrates, was eluted at the location of the syntheticlld -tripeptide δ-(l -α-aminoadipyl)-l -cysteinyl-d -valine. Since this compound was also labeled when the cultures were incubated withdl -[6-14 C]α-aminoadipic acid,l -[3,3′-3 H]cystine, ordl -[1-14 C]valine, its identity with the syntheticlld -tripeptide can be accepted. No δ-(l -α-aminoadipyl)-l -cysteine orlll -tripeptide were detected. The implications of these findings for tripeptide and penicillin biosynthesis are discussed.