Further evidence for the involvement of a monocyclic β-lactam in the enzymatic conversion of δ-L-α-aminoadipoyl-L-cysteinyl-D-valine into isopenicillin N.
Incubation of δ--α-aminoadipoyl--[3-13Ccysteinyl--[3-2H]valine with IsopenicillinNSynthase (IPNS) resulted in the observation of a ‘shuntmetabolite’, which we believe is formed from the collapse of an enzyme bound monocyclic β-lactam intermediate. Chemical studies into the origin of the shuntmetabolite suggest its formation occurred after initial β-lactam ring closure. Further chemical studies