The Rate of ATP Hydrolysis Catalyzed by Reconstituted CF0F
نویسنده
چکیده
The conditions for optimal rates of ATP hydrolysis catalyzed by the chloroplast ATP-synthase (A TPase), CFoF,, after isolation and reconstitution into asolectin liposomes have been investi gated. The rate of ATP hydrolysis was measured either after oxidation of CF0F, (by incubation with iodosobenzoate) or after reduction of CFoF, (by incubation with dithiothreitol). In both cases a rate of about 1 -2 ATP (CF0F i-s)“ ‘ was observed under uncoupled conditions. If the proteoliposomes are first energized by an acid-base transition and a K"/valinomycin diffusion poten tial, the uncoupled rate of ATP hydrolysis is about 1 -2 ATP (CFnF, s ) '1 for the oxidized enzyme and about 20 for the reduced species. This rate is about a factor 2 smaller than that observed in chloroolasts under the same conditions.
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