Westerhoff H V, Simonetti A L, Van Dam K
Biochem J. 1981 Nov 15;200(2):193-202. doi: 10.1042/bj2000193.
The hypothesis of 'localized' chemiosmosis have been put to an experimental test in the system of oxidative phosphorylation by rat liver mitochondria. We find that the variation of the ratio of phosphate potential to delta muH with delta muH does not depend on how delta muH is varied. This is in conflict with hypotheses of localized chemiosmosis. Of all coupling hypotheses, only the parallel-coupling hypothesis can explain the observations, unless variation of the H+/ATP stoichiometry of the ATPase proton pump is accepted. In the latter case. 'macroscopic' chemiosmosis can explain the observations equally well as hypotheses of localized chemiosmosis. It is concluded that either variation of H+/ATP stoichiometries must be accepted, or that the parallel-coupling hypothesis should be reformulated so that it becomes open to experimental tests.
“局部”化学渗透假说已在大鼠肝脏线粒体氧化磷酸化系统中进行了实验检验。我们发现，磷酸势与ΔμH的比值随ΔμH的变化并不取决于ΔμH是如何变化的。这与局部化学渗透假说相矛盾。在所有的偶联假说中，只有平行偶联假说能够解释这些观察结果，除非接受ATP酶质子泵的H⁺/ATP化学计量比发生变化。在后一种情况下，“宏观”化学渗透与局部化学渗透假说一样能够很好地解释这些观察结果。结论是，要么必须接受H⁺/ATP化学计量比的变化，要么应该重新阐述平行偶联假说，使其能够接受实验检验。
