Isopenicilin N synthase: A new mode of reactivity

Article abstract of DOI:10.1016/S0040-4020(01)82003-2

Incubation of L-δ-(α-aminoadipoyl)-L-(3,3-difluorohomocysteinyl)-D-valine [an analogue of the natural substrate: L-δ-(α-aminoadipoyl)-L-(cysteinyl)-D-varine] with isopenicillin N synthase (IPNS) resulted in the production of a thiocarboxylic acid, i.e. both equivalents of the dioxygen cosubstrate were utilised to oxidise a single carbon of the cysteinyl analogue. This result and others are rationalised in terms of mechanistic proposals for the first ring closure by IPNS. The synthesis of L-difluorohomocysteine and related structures, via 3,3-difluoro-β-lactams, is described.