Vinogradov A D
Department of Biochemistry, School of Biology, Moscow State University, Moscow 119899, Russian Federation.
J Exp Biol. 2000 Jan;203(Pt 1):41-9. doi: 10.1242/jeb.203.1.41.
H(+)-ATP synthase (F(1)F(o) ATPase) catalyzes the synthesis and/or hydrolysis of ATP, and the reactions are strongly affected by all the substrates (products) in a way clearly distinct from that expected of a simple reversibly operating enzyme. Recent studies have revealed the structure of F(1), which is ideally suited for the alternating binding change mechanism, with a rotating gamma-subunit as the energy-driven coupling device. According to this mechanism ATP, ADP, inorganic phosphate (P(i)) and Mg(2+) participate in the forward and reverse overall reactions exclusively as the substrates and products. However, both F(1) and F(1)F(o) demonstrate non-trivial steady-state and pre-steady-state kinetics as a function of variable substrate (product) concentrations. Several effectors cause unidirectional inhibition or activation of the enzyme. When considered separately, the unidirectional effects of ADP, P(i), Mg(2+) and energy supply on ATP synthesis or hydrolysis may possibly be explained by very complex kinetic schemes; taken together, the results suggest that different conformational states of the enzyme operate in the ATP hydrolase and ATP synthase reactions. A possible mechanism for an energy-dependent switch between the two states of F(1)F(o) ATPase is proposed.
H(+)-ATP合酶（F(1)F(o) ATP酶）催化ATP的合成和/或水解，并且这些反应受到所有底物（产物）的强烈影响，其方式明显不同于简单可逆操作酶的预期方式。最近的研究揭示了F(1)的结构，它非常适合交替结合变化机制，其中旋转的γ亚基作为能量驱动的偶联装置。根据该机制，ATP、ADP、无机磷酸（P(i)）和Mg(2+)仅作为底物和产物参与正向和反向的整体反应。然而，F(1)和F(1)F(o)都表现出作为可变底物（产物）浓度函数的非平凡稳态和预稳态动力学。几种效应物会导致酶的单向抑制或激活。单独考虑时，ADP、P(i)、Mg(2+)和能量供应对ATP合成或水解的单向影响可能可以用非常复杂的动力学方案来解释；综合起来，结果表明酶的不同构象状态在ATP水解酶和ATP合酶反应中起作用。提出了一种F(1)F(o) ATP酶两种状态之间能量依赖性转换的可能机制。
