The reaction of an alpha-aza-amino acid derivative with chymotrypsin and its use as a ligand for covalent affinity purification.

1. Chymotrypsin is inactivated by N-acetyl-alpha-azaphenylalanine phenyl ester (phenyl N(2)-acetyl-N(1)-benzylcarbazate) in a stoicheiometric reaction. 2. The inactivation is reversible spontaneously (first-order rate constant is 1.2x10(-4)s(-1)) and accelerated by the presence of hydroxylamine. 3. Polymers based on polyacrylamide and carrying ligands containing the alpha-azaphenylalanine phenyl ester group were prepared. 4. Chymotrypsin reacts with these polymers and is removed by them from solution. Trypsin reacts less rapidly. 5. Chymotrypsin is slowly released from the polymer spontaneously and more rapidly on treatment with hydroxylamine. 6. The reaction of trypsin can be inhibited by competitive inhibitors. 7. Chymotrypsin was separated from trypsin by the selective bonding of chymotrypsin on to and its subsequent liberation from one of the polymers described.