Incorporation of labeled precursors into A16886B, a novel -lactam antibiotic produced by Streptomyces clavuligerus.

The incorporation of C-14 from amino acids into A16886B, 7-(5-amino-5-carboxyvaleramido)-7-methoxy-3-carbamoyloxymethyl-3-cephem-4- carboxylic acid, by Streptomyces clavuligerus is reported. As with cephalosporin C biosynthesis by the mold Cephalosporium acremonium, labels from cysteine, valine, and alpha-amino-adipic acid were incorporated. Unlike cephalosporin C, in A16886B label from lysine was incorporated into the alpha-aminoadipic acid side chain. Label from methionine-(14)C-methyl was incorporated into the methoxyl group. The relative percentage of incorporation of (3)H and (14)C from doubly labeled cystine suggests the improbability of the C-7 methoxyl group arising from an intermediate containing a double bond between C-6 and C-7.