Chloroplast ATPase (CF1) was isolated from spinach, pea and maize thylakoids by EDTA extraction followed by anion-exchange chromatography. CF1 was purified and resolved by HPLC into integral CF1, and CF1 lacking the δ & ɛ subunits: CF1(–δ) and CF1(–ɛ). Washing Mono-Q-bound CF1 with alcohol-containing buffers followed by elution without alcohol produced the β subunit and in separate peaks CF1(–δ) and CF1(–ɛ). Elution from Mono Q in the presence of tenside yielded a βδ fragment, CF1(–δ) and CF1(–δɛ).
Chloroplasts were CF1-depleted by EDTA extraction. Reconstitution of photophosphorylation in these ‘EDTA vesicles’ was obtained by addition of CF1 and its fragments. CF1, CF1(–δ) and CF1(–δɛ) were active with cross-reactivity between spinach, pea and maize. δ-containing CF1 always reconstituted higher activities than δ-deficient CF1. The βδ fragment and dicyclohexylcarbodiimide (DCCD)-inhibited CF1 also were reconstitutively active while β and DCCD-inhibited CF1(–δ) were not.
These results support the notion that subunit δ can function as a stopcock to the CF0 proton channel as proposed by Junge, W., Hong, Y. Q., Qian, L. P. and Viale, A. [(1984) Proc. Natl Acad. Sci. USA 81, 3078–3082].