Abstract
The H+-ATPase from chloroplasts (CF0F1) was isolated, purified and reconstituted into liposomes from phosphatidylcholine/phosphatidic acid. A transmembrane pH difference, ΔpH, and a transmembrane electric potential difference, ΔΨ, were generate by an acid/base transition. The rate of ATP synthesis was measured at constant ΔpH and constant ΔΨ as a function of temperature between 5°C and 45°C. The activation energy was 55 kJ mol−1.
CF0F1 was coreconstituted with bacteriohodopsin at a molar ratio of approximately 1:170 in the same type of liposomes. Illumination of the proteoliposomes leads to proton transport into the vesicles generating a constant ΔpH = 1.8. The dependence of the rate of ATP synthesis on ADP concentration was measured with CF0F1 in the oxidized state, Eox, and in the reduced state, Ered. The results can be described by Michaelis-Menten kinetics with the following parameters: Vmax= 0.5 s−1, Km= 8 µLM for Eox and Vmax= 2.0 s−1, Km= 8 µLM for Ered.
CF0F1 was coreconstituted with bacteriohodopsin at a molar ratio of approximately 1:170 in the same type of liposomes. Illumination of the proteoliposomes leads to proton transport into the vesicles generating a constant ΔpH = 1.8. The dependence of the rate of ATP synthesis on ADP concentration was measured with CF0F1 in the oxidized state, Eox, and in the reduced state, Ered. The results can be described by Michaelis-Menten kinetics with the following parameters: Vmax= 0.5 s−1, Km= 8 µLM for Eox and Vmax= 2.0 s−1, Km= 8 µLM for Ered.
Original language | English |
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Pages (from-to) | 287-291 |
Journal | European Journal of Biochemistry |
Volume | 210 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Jan 1992 |
MoE publication type | Not Eligible |