Kinetics of electron transfer through the respiratory chain
Kinetics of electron transfer through the respiratory chain
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DOI：
10.1016/s0006-3495(02)73945-3
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发表时间：
2002-10-01
影响因子：
3.4
通讯作者：
Bethke, CM
中科院分区：
文献类型：
--
作者：
Jin, QS;Bethke, CM
我们表明，在线粒体和呼吸原核细胞中，电子通过呼吸链的速率是由三个术语的产品，一个描述电子捐赠，一个接受，和第三，热力学驱动器。我们将非平衡态热力学理论应用于质子迁移和能量守恒的化学渗透模型。这种方法导致一个封闭的形式的表达，预测稳态电子通量作为一个功能的化学条件和质子动力的线粒体内膜或原核细胞质膜。速率表达式，考虑到反向和正向电子流，是第一个考虑到呼吸速率的热力学和动力学控制。在特定条件下，该表达式可以简化，以给出细胞生理学和微生物生态学中常见的各种形式的速率定律。该表达式解释了通量对电位梯度的非线性依赖关系，对底物浓度的双曲线依赖关系，以及反应产物的抑制作用。它为研究异常条件下的生命提供了理论基础，如碱性沃茨中的微生物呼吸。
We show that the rate at which electrons pass through the respiratory chain in mitochondria and respiring prokaryotic cells is described by the product of three terms, one describing electron donation, one acceptance, and a third, the thermodynamic drive. We apply the theory of nonequilibrium thermodynamics in the context of the chemiosmotic model of proton translocation and energy conservation. This approach leads to a closed-form expression that predicts steady-state electron flux as a function of chemical conditions and the proton motive force across the mitochondrial inner membrane or prokaryotic cytoplasmic membrane. The rate expression, derived considering reverse and forward electron flow, is the first to account for both thermodynamic and kinetic controls on the respiration rate. The expression can be simplified under specific conditions to give rate laws of various forms familiar in cellular physiology and microbial ecology. The expression explains the nonlinear dependence of flux on electrical potential gradient, its hyperbolic dependence on substrate concentration, and the inhibiting effects of reaction products. It provides a theoretical basis for investigating life under unusual conditions, such as microbial respiration in alkaline waters.