Behaviour of α-aminoadipylcysteine and glutamylcysteine in the presence of intact and disrupted mycelium of a Cephalosporium sp

delta-(l-alpha-Aminoadipyl)-l-cysteine, the corresponding d- and dl-alpha-aminoadipyl isomers, delta-(dl-alpha-amino[6-(14)C]adipyl)-l-cysteine and gamma- and alpha-l-glutamyl-l-cysteine were synthesized. 2. The behaviour of delta-(l-aminoadipyl)-l-cysteine and the corresponding d- and dl-alpha-aminoadipyl isomers was studied in the presence of suspensions of intact mycelium of a Cephalosporium sp., suspensions treated ultrasonically and extracts obtained by grinding with alumina. 3. With intact mycelium the l-alpha-aminoadipyl isomer was removed more rapidly from the extracellular fluid than the corresponding d-isomer. 4. Addition of delta-(dl-alpha-amino[6-(14)C]adipyl)-l-cysteine to suspensions of intact mycelium led to the labelling of extracellular and intracellular penicillin N and cephalosporin C, but also to extensive hydrolysis of the dipeptide. 5. Broken-cell systems hydrolysed delta-(l-alpha-aminoadipyl)-l-cysteine and the corresponding d-alpha-aminoadipyl isomer, but the former was hydrolysed more readily than the latter. 6. gamma- and alpha-l-Glutamyl-l-cysteine were also hydrolysed but delta-(l-alpha-aminoadipyl)-l-cysteinyl-l-valine was not. 7. Only part of the enzyme activity in broken-cell systems responsible for the hydrolysis of delta-(alpha-aminoadipyl)-l-cysteine was present in the supernatant obtained on centrifugation at 20000g. 8. Possible implications of these findings are discussed.