Non-thermal Effects of a Ceramics Heater Radiation on Xanthine Oxidase Activity

Abstract

The non-thermal effects of ceramics heater radiation on xanthine oxidase activity have been investigated using the enzyme, substrate, and competitive inhibitors which were irradiated on cooling. The K_m and V_max in the irradiated enzyme system were reduced to 51% and 85% of the non-irradiated control, respectively. The K_i for a competitive inhibitor, folic acid, in the irradiated enzyme system decreased to 22% of the non-irradiated control. A steady-state molecular kinetic analysis for the reaction estimates that the irradiated enzyme may be kept in a folding state, and the formation of a Michaelis complex has been accelerated, and the activated Michaelis complex has been stabilized, and that a solvation or an electrostriction of xanthine, folate, and an active center of the enzyme with water may be promoted by irradiating the components in an aqueous solution, by which modification of the enzyme activity has been regulated.