title: Biosynthesis of a 7-alpha-methoxycephalosporin. Incorporation of molecular oxygen.
abstract: A 7-alpha-methoxycephalosporin containing a carbamoyloxymethyl substituent at C-3 (cephamycin C) has been isolated from the extracellular fluid of an aqueous suspension of Streptomyces clavuligerus shaken in the presence of 18O2. The cephalosporin has been converted into its N-acetyl dimethyl ester and the distribution of 18O in the latter determined by chemical-ionization mass spectrometry. The results indicate that the oxygen atom of the methoxy group, as well as that linked to the exocyclic methylene group at C-3, is derived from molecular O2.
mesh_terms: D002511:Cephalosporins / Q000096:biosynthesis*; D002513:Cephamycins / Q000096:biosynthesis* / Q000302:isolation & purification; D055598:Chemical Phenomena; D002621:Chemistry; D013058:Mass Spectrometry; D010100:Oxygen / Q000378:metabolism*; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D002513:Cephamycins; D010100:Oxygen