A minimum catalytic unit of F1-ATPase shows non-cooperative ATPase activity inherent in a single catalytic site with a Km 70 microM.

F1-ATPase has three interacting catalytic sites and shows complicated kinetics. Here, we report reconstitution of a complex, most likely composed of one alpha subunit and one beta 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 Km(ATP) of 70 microM and a Vmax 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.