Is localized chemiosmosis necessary in mitochondria? Is Lee's TELP protonic capacitor hypothesis a reasonable model?

Mitochondrial Communications Pub Date : 2024-01-01 DOI:10.1016/j.mitoco.2024.06.001

Todd P. Silverstein

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Abstract

Recent high-resolution pH measurements in mitochondria show ΔpH across the F₁F₀ ATP synthase to be quite low, 0.07–0.32. Our meta-analysis of published values of transmembrane potential ( $Δ ψ$ ) shows it to be identical in vivo and in vitro: -159 ± 16 mV. With the low ΔpH, the thermodynamic efficiency of proton-driven ATP synthesis exceeds 100 % for average- and low-potential (−123 mV) mitochondria, and possibly also for high-potential (−180 mV) mitochondria. Efficiencies exceeding 100 % may violate the second law of thermodynamics, and suggest a need for localized chemiosmosis, i.e., the existence of a membrane surface ΔpH that exceeds the bulk phase ΔpH by at least 0.2 units in high-potential mitochondria, and by 1.1 units in low-potential mitochondria. The lack of equilibration between protons in the bulk phase and those at the membrane surface is explained by two models which we discuss and compare: the potential well/barrier model, and the TELP protonic capacitor model.

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线粒体中的局部化合作用是否必要？李的 TELP 质子电容器假说是一个合理的模型吗？

最近在线粒体中进行的高分辨率 pH 测量显示，F1F0 ATP 合酶跨膜电位（ΔpH）相当低，为 0.07-0.32。我们对已发表的跨膜电位（Δψ）值进行的元分析表明，体内和体外的跨膜电位相同：-159 ± 16 mV。由于ΔpH 较低，质子驱动的 ATP 合成热力学效率在平均电位和低电位（-123 mV）线粒体中超过 100%，在高电位（-180 mV）线粒体中也可能超过 100%。超过 100 % 的效率可能违反热力学第二定律，并表明需要局部化合渗透，即膜表面 ΔpH 在高电位线粒体中至少超过体相 ΔpH 0.2 个单位，在低电位线粒体中超过 1.1 个单位。我们讨论并比较了两种模型：电位井/屏障模型和 TELP 质子电容器模型，这两种模型都可以解释体相质子和膜表面质子之间缺乏平衡的现象。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Mitochondrial Communications

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