Reverse catalysis of elastase from porcine pancreas in frozen aqueous systems.

The reverse action of a trypsin-free elastase isolated from porcine pancreas was studied in frozen aqueous systems. Under frozen state conditions, porcine pancreatic elastase was able to catalyse peptide bond formation more effectively than in solution at room temperature. The acceptance of free amino acids as nucleophilic amino components indicates a changed specificity of the endoprotease in frozen reaction mixtures. In elastase-catalysed formation of Ser-, Ile- and Val-X-bonds in frozen aqueous reaction mixtures, peptide yields obtained depended on the P1 amino acid and the acyl donor chain length.