Covalently immobilised penicillin G acylase (PGA-450) accepts in toluene, at controlled water activity (aw), a broad range of amino compounds as nucleophiles in kinetically controlled acylation. Hydrolytic reactions were prevented and complete conversions were achieved in short times even when working with an equimolar concentration of the substrates. The recovery of the products was facile, leading to high isolation yields. The obtained N-acylated derivatives of L-amino acids can be used in further reactions, since no purification steps are required in such conditions. This opens new perspectives to the application of PGA in selective protection of the amino function for peptide synthesis. Ali attempts to perform esterification and transesterification reactions with PGA in toluene, at the same aw as used for the acylation of amino compounds, were unsuccesful.
