The utilization of L-cystinyl-L-valine for penicillin biosynthesis

Biosynthesis of chloramphenicol. II. p-Aminophenylalanine as a precursor of the p-nitrophenylserinol moiety

DL-p-Aminophenylalanine, DL-p-nitrophenylalanine, DL-threo-phenylserine, DL-phenyllactic acid, DL-p-hydroxyphenyllactic acid, D-phenylalanine, L-phenylalanol, DL-threo-β-phenylglyceric acid, D-threo-p-aminophenylserinol, and D-threo-p-nitrophenylserinol, all specifically labeled with14C, were tested as precursors of chloramphenicol in cultures of Streptomyces sp. 3022a. Only DL-p-amino-phenylalanine-α-14C was efficiently incorporated into the p-nitrophenylserinol moiety of the antibiotic. All of the radioactivity was found in the aminomethine carbon. Protein phenylalanine and tyrosine were only weakly labeled, and it is concluded that p-aminophenylalanine is a specific precursor of chloramphenicol.