title: Cell-free ring expansion of penicillin N to deacetoxycephalosporin C by Cephalosporium acremonium CW-19 and its mutants.
abstract: To examine microbiological ring expansion of penicillin N to a cephalosporin, we obtained five mutants of Cephalosporium acremonium blocked in beta-lactam antibiotic biosynthesis from 2500 survivors of mutagenesis. In submerged fermentation, mutants M-0198, M-0199, and M-2351 produced no beta-lactam antibiotic (type A), whereas mutants M-1443 and M-1836 formed penicillin N but not cephalosporin C (type B). Cell-free extracts of type A mutants converted penicillin N to a cephalosporin; those of type B mutants did not. The product of the cell-free reaction was identified as deacetoxycephalosporin C by thin-layer chromatography, paper chromatography, paper electrophoresis, and enzyme tests. These data strongly support our hypothesis that penicillin N is an intermediate of cephalosporin biosynthesis.
mesh_terms: D000164:Acremonium / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002474:Cell-Free System; D002511:Cephalosporins / Q000096:biosynthesis*; D055598:Chemical Phenomena; D002621:Chemistry; D009154:Mutation; D010405:Penicillinase / Q000378:metabolism
chemical_list: D002511:Cephalosporins; D010405:Penicillinase