A minimum catalytic unit of F1‐ATPase shows non‐cooperative ATPase activity inherent in a single catalytic site with a Km 70 μM

Abstract

F₁‐ATPase has three interacting catalytic sites and shows complicated kinetics. Here, we report reconstitution of a complex, most likely composed of one α subunit and one β subunit, with a single catalytic site from thermophilic Bacillus PS3 F₁‐ATPase on the solid surface. The complex has an ATPase activity which obeys a simple non‐cooperative kinetics with a K _m(ATP) of 70 μM and a V _max of 0.1 unit/mg. Different from F₁‐ATPase, the complex is not inactivated by 7‐chrolo‐4‐nitrobenzofrazan. Thus, the inherent activity attributable to a single catalytic site unaffected by other catalytic sites of F₁‐ATPase is characterized.