NONTHERMAL EFFECTS OF A CERAMICS HEATER RADIATION ON XANTHINE-OXIDASEACTIVITY

The non-thermal effects of ceramics heater radiation on xanthine oxida se activity have been investigated using the enzyme, substrate, and co mpetitive inhibitors which were irradiated on cooling. The K(m) and V( max) in the irradiated enzyme system were reduced to 51% and 85% of th e non-irradiated control, respectively. The K(i) for a competitive inh ibitor, folic acid, in the irradiated enzyme system decreased to 22% o f the non-irradiated control. A steady-state molecular kinetic analysi s for the reaction estimates that the irradiated enzyme may be kept in a folding state, and the formation of a Michaelis complex has been ac celerated, and the activated Michaelis complex has been stabilized, an d 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 en zyme activity has been regulated.