Papain-catalyzed hydrolysis of and amino acid incorporation into BSA and Zein substrates in low water organic media

Papain, either modified with polyethylene glycol (PEG) or in the form of a suspended powder, was used to catalyze the digestion of protein substrates in organic solvents to gain insights into protein-protein interactions in media of this kind. Bovine serum albumin was efficiently hydrolyzed in toluene containing added water. The extent of proteolysis, as estimated by amino group determination, depended on the water concentration and, under the optimal condition, was 20% higher than that obtained in aqueous media using the same enzyme/substrate ratio