Westerhoff H V, Chen Y
Proc Natl Acad Sci U S A. 1985 May;82(10):3222-6. doi: 10.1073/pnas.82.10.3222.
Theoretical free-energy coupling systems in which the free energy coupling intermediate (e.g., the proton) occurs only in small numbers of molecules per coupling unit are shown to exhibit a number of peculiar properties: (i) the reactions involving the intermediates do not follow conventional kinetic (or nonequilibrium thermodynamic) rate laws in terms of the average concentration or chemical potential of the intermediate, (ii) the variation of the output reaction rate with the average intermediate concentration (or apparent chemical potential) is not unequivocal but depends on whether the input reaction or the leak is varied to alter that concentration, and (iii) when the apparent free energy contained in the average concentration of the intermediate is compared with the average free energy recovered in the output reaction, apparent violations of the second law of thermodynamics can occur. These phenomena are reminiscent of experimental observations in proton-linked free-energy transducing systems that suggest a more direct coupling between electron transfer chains and H+-ATPases than only through a bulk proton gradient, delta muH. Consequently, the chemiosmotic coupling theory can account for those observations if it limits the number of free energy coupling protons per chemiosmotic coupling unit to small values.
理论自由能耦合系统中，自由能耦合中间体（如质子）在每个耦合单元中仅少量分子存在，已证明其具有许多特殊性质：（i）涉及中间体的反应，就中间体的平均浓度或化学势而言，并不遵循传统动力学（或非平衡热力学）速率定律；（ii）输出反应速率随中间体平均浓度（或表观化学势）的变化并不明确，而是取决于改变该浓度时是输入反应还是泄漏发生了变化；（iii）当将中间体平均浓度中所含的表观自由能与输出反应中回收的平均自由能进行比较时，可能会出现明显违反热力学第二定律的情况。这些现象让人想起质子关联自由能转导系统中的实验观察结果，这些结果表明电子传递链与H⁺ - ATP酶之间的耦合比仅通过整体质子梯度ΔμH更为直接。因此，如果化学渗透耦合理论将每个化学渗透耦合单元中自由能耦合质子的数量限制为较小值，那么它就能解释这些观察结果。
