Immobilization of penicillin G acylase on aminoalkylated polyacrylic supports

A procedure is described for the immobilization of penicillin G acylase (PA) on Amberlite XAD7 modified by transamidation with 1,2-ethylenediamine and activated with glutaraldehyde. Reduction with sodium borohydride of the Schiff's bases formed between the amino groups of the protein and glutaraldehyde results in a dramatic improvement of the operational stability of the immobilized enzyme without affecting the catalytic activity. The enzyme kept in presence of the substrate, penicillin G, displays an increased stability with respect to that stored in pure phosphate buffer solution. The inactivation kinetics of the immobilized preparations of PA, determined in a continuous fixed bed reactor, as well as a discontinuous batch reactor, are reported.