Large-scale purification and characterization of the five subunits of F1-ATPase from pig heart mitochondria.

A large-scale purification procedure was developed to isolate the five subunits of F1-ATPase from pig heart mitochondria. The previously described procedure (Williams, N. and Pedersen, P.L. (1986) Methods Enzymol. 126, 484-489) to dissociate the rat liver F1-ATPase by cold treatment followed by warming at 37 degrees C has been adapted for the pig heart enzyme. Removal of endogenous nucleotides from that enzyme before dissociation led to the efficient separation of the alpha and gamma subunits from beta, delta and epsilon subunits. The beta subunit was purified in the hundred-milligram range by anion-exchange chromatography in the absence of any denaturing agent. This subunit was free from any bound nucleotide and almost no ATPase and adenylate kinase-like activities were detected. The delta and epsilon subunits were purified by reversed-phase chromatography (RP-HPLC) in the milligram range. As recently reported (Penin, F., Deléage, G., Gagliardi, D., Roux, B. and Gautheron, D.C. (1990) Biochemistry 29, 9358-9364), these purified subunits kept biophysical features of folded proteins and their ability to reconstitute the tight delta epsilon complex. The alpha and gamma subunits remained poorly soluble and required dissociation by 8 M guanidinium chloride prior to their purification by RP-HPLC. In addition, characterizations of the five subunits by IEF and SDS-polyacrylamide gel electrophoresis are reported, as well as ultraviolet spectra and solubility properties of the beta, delta and epsilon subunits.