INACTIVATION OF FIREFLY LUCIFERASE AND RAT ERYTHROCYTE ATPASE BY ULTRASOUND

Previous work in our laboratories has shown that, amongst other effect s, irradiation of frog skin with low intensity ultrasound causes reduc tions in the chemical driving force of the short-circuit current. This indicated that either the Na/K dependent ATPase or ATP availability w ere being reduced. We measured the effect of ultrasound irradiation on ATP and NA/K-dependent ATPase from inverted erythrocyte ghosts and on firefly luciferin and luciferase activity. Our findings demonstrate t hat ultrasonic cavitation-induced sonochemical reactions were responsi ble for irreversible inactivation of luciferase and ATPase but had lit tle or no effect on ATP and luciferin. We measured the levels of hydro gen peroxide generated by ultrasound under the conditions of our exper iments and found that it could account for only part of the enzyme ina ctivation observed. Free radical scavengers/antioxidants were capable of fully protecting the enzymes from ultrasound-induced inactivation. These findings demonstrate that, in addition to hydrogen peroxide, fre e radicals generated by ultrasound are responsible for the effects.