Biosynthesis of cephalosporin C from amino acids

Abstract

Cephalosporin-C produced by a Cephalo-sporium sp. in a complex medium containing DL-[1-Cl4]valine was radioactive. Its C14 was localized almost exclusively in the C5 frag-ment of the dihydrothiazine ring in the molecule which yields valine on hydrogenolysis. The addition of a mixture of DL-[3-Cl4]cystine and meso-[3-C14]cystine to the culture medium resulted in the production of radioactive cephalosporin-C. The major portion of the C14 in the molecule was present in a C2 fragment of the [beta]-lactam ring. Significant portions were also present in the C5 fragment of the dihydrothiazine ring and the a-aminoadipoyl side chain respectively. DL-[alpha]-Amino-[2-Cl4]adipic-acid was synthesized from [gamma]-bromobutyronitrile and diethyl acetamido-[2-C14]malonate. Cephalosporin-C produced in a medium to which this amino-acid was added was radioactive, and its Cl4 was almost exclusively present in the a-aminoadipoyl group of the molecule. Lysine from the mycelium of the Cephalosporium sp. grown in the presence of DL-[alpha]-amino[2-Cl4]adipic-acid was radioactive. But the proportion of the added radioactivity was much smaller than with the experiments involving labelled valine and cystine. Less than 0.1% was recovered in the respiratory CO2.