Behaviour of tritium-labelled isopenicillin N and 6-aminopenicillanic acid as potential penicillin precursors in an extract of Penicillum chrysogenum

Abstract

1. 3H was incorporated into solvent-soluble penicillin from isopenicillin N and 6-aminopenicillanic acid 3H-labelled in the 2β-methyl group when the labelled compounds were incubated with a crude extract of Penicillum chrysogenum. 2. With a soluble protein fraction of the extract incorporation from isopenicillin N occurred on addition of phenyl-acetyl-CoA. 3. Labelled benzylpenicillin was isolated after incubation of the crude extract with phenylacetyl-CoA and isopenicillin and the addition of unlabelled benzylpenicillin as a carrier. 4. No incorporation of 3H into solvent-soluble penicillin was detected on incubation of these extracts with penicillin N.