Intact incorporation of δ-(α-L-aminoadipoyl)-L-[3-13C]cysteinyl-D-[15N]valine into isopenicillin N. Observation of one-bond 13C–15N coupling

Abstract

δ-(α-L-Aminoadipoyl)-L-[3-¹³C]cysteinyl-D-[¹⁵N]valine (1a) was efficiently transformed into [4-¹⁵N,5-¹³C]isopenicillin N (2a) by a cell-free system prepared from cells of Cephalosporium acremonium CW19. ¹³C N.m.r. spectra of deproteinated incubation mixtures showed ¹³C–¹⁵N coupling of the enriched C-5 resonance of the product, but offered no evidence for the presence of intermediate species.