Azobenzene modified papain, reveals photoregulation toward hydrolysis of N alpha-benzoyl-DL-arginine-4-nitroanilide. The association constants of thiophenefulgide modified concanavolin A (Con. A) towards monosaccharides is reversibly photoregulated. Immobilized cr-chymotrypsin in photochromic copolymers exhibits "ON-OFF" photoregulation towards the hydrolysis of N-(3-carboxpropionyl)-L-phenylalanine p-nitroanilide.