The Radiation Chemistry of Papain in Dilute Aqueous Solutions

The effects of Co/sup 60/ gamma irradiation on solutions of crystalline papain were investigated by means of ultraviolet and infrared spectrometry, ultracentrifugation, appearance of opalescence and turbidity, and determination of the ability of the enzyme to catalyze the hydrolysis of N-bertzoyl-L-arginine amlde, The catalytic activity decreased exponentially with radiation dose in air- saturated solutions for any given initial activity. The initial yields, however, almost doubled as the enzyme concentration was increased from 45 to 380 mg per 100 ml. Displacement of air by He had essentially no effect on the yields. The catalytic activity was lost more rapidly at pH values of 3.0 and 9.0 than at the natural pH of 5.35. The ultraviolet absorption spectrum showed a decreased at the 280 m mu peak with small radiation doses, then increased greatiy at all wave lengths with higher doses. Opalescence and turbidity occurred in irradiated solutions having pH values of 7 or greater. The infrared and Schlieren patterns of 1% solutions showed essentially no change. (auth)