A MINIMUM CATALYTIC UNIT OF F1-ATPASE SHOWS NONCOOPERATIVE ATPASE ACTIVITY INHERENT IN A SINGLE CATALYTIC SITE WITH A K(M)70 MU-M

F-1-ATPase has three interacting catalytic sites and shows complicated kinetics. Here, we report reconstitution of a complex, most likely co mposed of one alpha subunit and one beta subunit, with a single cataly tic site front thermophilic Bacillus PS3 F-1-ATPase on the sold surfac e. The complex has an ATPase activity which obeys a simple non-coopera tive kinetics with a K-m(ATP) of 70 mu M and a V-max of 0.1 unit/mg. D ifferent from F-1-ATPase, the complex is not inactivated by 7-chrolo-4 -nitrobenzofrazan. Thus, the inherent activity attributable to a singl e catalytic site unaffected by other catalytic sites of F-1-ATPase is characterized.