Functionally distinct beta subunits in F1-adenosinetriphosphatase.

A method has been developed for the effective inactivation of bovine heart mitochondrial F1-ATPase (MF1) by partially dissociating its subunits with 3 M LiCl at 0 degree C and for the subsequent partial restoration of its ATPase activity by making the subunits reassociate upon the removal of LiCl by centrifugal gel filtration at room temperature through Sephadex G-25-80 which has been pre-equilibrated with buffer containing 3 mM ATP. When covalently labeled MF1 with approximately one 7-[4-nitro-2,1,3-benzoxadiazole] label/MF1 was subjected to this type of partial dissociation-reassociation treatment, its ATPase activity could be increased from 1.48 to 18.0 mumol of ATP min-1 mg-1 without losing the covalent label. The experimental results are incompatible with models for F1-ATPase with either 3 or 2 equivalent alternating catalytic sites, but are consistent with the model with 1 active catalytic site and 2 interacting regulatory sites.