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The production of penicillin was inhibited by neutral amino acids in a resting cell system of Penicillium chrysogenum with cycloheximide. The inhibitory action was prevented by preincubation Vyith glutathione, even though this stimulated uptake of the neutral amino acid glutamine. Chromatographic analysis of extracts obtained from cells incubated with labelled glutamine revealed that radioactivity was taken up through the formation of two intermediates; L-y-glutamyl-L-glutamine and 6-(L-a-aminoadipyl)-L-glutamine. In a resting cell system prepared from cultures previously grown in the presence of 50 mM-L-lySine, a condition which restrains a-aminoadipate and penicillin formation, uptake of glutamine was 80% inhibited. We propose that the penicillin precursor 6-(L-a-aminoadipyl)-L-cysteinyl-D-valine, which is structurally related to glutathione, is also utilized in the uptake of neutral amino acids.

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