Uni‐site ATP synthesis in thylakoids

FEBS Letters

Fromme, Petra¹  Labahn, Andreas¹  Gräber, Peter² 

[1] Max Voltner Institut für Biophysikalische und Physikalische Chemie, Technische Universität Berlin, Str.d. 17. Juni 135, D-1000 Berlin 12, FRG;Biologisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 7000 Stuttgart 80, FRG

关键词: Chloroplast;    ATPase H+;    CF0F1;    Uni-site catalysis;    ATP synthesis;    CF0F1;    H+-translocating ATPase (‘ATP-synthase’) from chloroplasts;   

DOI  :  10.1016/0014-5793(90)80385-V

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Uni-site ATP synthesis was measured with thylakoids. The membrane-bound ATP-synthase, CF₀F₁ was brought into the active, reduced state by illumination in the presence of thioredoxin, dithiothreitol and phosphate. This enzyme contains two tightly bound ATP per CF_oF₁. ATP was released from the enzyme when ADP was added in substoichiometric amounts during illumination. Experiments with [¹⁴C]ADP indicated that after binding the same nucleotide was phosphorylated and released as [¹⁴C]ATP, i.e. only one site is involved in ATP-synthesis (uni-site ATP-synthesis'). The two tightly bound ATP are not involved in the catalytic turnover. The rate constant for ADP binding was (4 ± 2) × 10⁶ M⁻¹s⁻¹. Compared to deenergized conditions the rate constant for ADP binding and that for ATP-release were drastically increased, i.e. membrane energization increased the rate constants for the ATP-synthesis direction.

【 授权许可】

Unknown