Penicillin biosynthesis. On the stereochemistry of carbon–sulphur bond formation with modified substrates

Abstract

Enzymatic conversion of the two modified substrates (S-α-amino-δ-adipyl)-S-cysteinyl-(2R,3R)-3-²H-α-aminobutyrate (2c) and (S-α-amino-δ-adipyl)-S-cysteinyl-(2R,3S)-3-²H-α-aminobutyrate (2d) by the enzyme isopenicillin N synthetase gave from both precursors the same penam product, namely (2S)-2-deuterio-norisopenicillin N, indicating that this enzyme is capable of forming carbon–sulphur bonds by retention and also inversion pathways respectively.