Purification and Reconstitution of Active Chloroplast F,,*

Chloroplast Fo (CF,) was purified from the ATP synthase by Zwittergent 3-12 treatment and DEAE-Trisacryl anion exchange chromatography. Purified CFO contains four subunits corresponding to subunits I, II, III, and IV. CFo mediated proton translocation across the membrane after incorporation into asolectin liposomes. The CFo-mediated proton transport was inhibited by N,N’-dicyclohexylcarbodiimide and the binding of chloroplast coupling factor 1 (CF,). Rebinding of CFI to CFo liposomes resulted in reconstitution of N,N’-dicyclohexylcarbodiimide and uncoupler sensitive energy-transducing activities. Like CFo in native thylakoid membranes, purified CFo bound CFI as well as CF1 deficient in either the 6 or c subunits.