Use of high acyl donor concentrations leads to penicillin acylase inactivation in the course of peptide synthesis

Enzyme inactivation has been observed in the course of penicillin acylase-catalyzed hydrolysis and aminolysis of d-phenylglycine amide. Inactivation was very sensitive to the d-phenylglycine amide concentration: at pH 9.5, 25 °C and 400 mM substrate, penicillin acylase lost more than 90% of its initial catalytic activity in half an hour, in the presence of 100 mM substrate, 50% of the initial activity in two hours, whereas in the absence of substrate, no significant enzyme inactivation was observed in three hours. Observed enzyme inactivation limits use of high acyl donor concentrations at penicillin acylase-catalyzed peptide synthesis.