Incorporation of Labeled Precursors into A16886B, a Novel β-Lactam Antibiotic Produced by Streptomyces clavuligerus

Abstract

<jats:p> 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 <jats:italic>Streptomyces clavuligerus</jats:italic> is reported. As with cephalosporin C biosynthesis by the mold <jats:italic>Cephalosporium acremonium</jats:italic> , labels from cysteine, valine, and α-amino-adipic acid were incorporated. Unlike cephalosporin C, in A16886B label from lysine was incorporated into the α-aminoadipic acid side chain. Label from methionine- <jats:sup>14</jats:sup> <jats:italic>C-methyl</jats:italic> was incorporated into the methoxyl group. The relative percentage of incorporation of <jats:sup>3</jats:sup> H and <jats:sup>14</jats:sup> 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.