Penicillins and cephalosporins are β-lactam antibiotics widely used in human medicine. The biosynthesis of these compounds starts by the condensation of the amino acids L-α-aminoadipic acid, L-cysteine and L-valine to form the tripeptide δ-L-α-aminoadipyl-l-cysteinyl-D-valine catalysed by the non-ribosomal peptide 'ACV synthetase'. Subsequently, this tripeptide is cyclized to isopenicillin N th...
