Kitasato Hiroshi
Department of Physiology, Shiga University of Medical Science, Ohtsu, Shiga 520-2192, Japan.
J Plant Res. 2003 Oct;116(5):401-18. doi: 10.1007/s10265-003-0108-4. Epub 2003 Aug 13.
The resting membrane potential of Nitella cells shifts in parallel with the change in H+ equilibrium potential, but is not equal to the H+ equilibrium potential. The deviation of the membrane potential from the H+ equilibrium potential depends on the extrusion rate of H+ by the electrogenic H+-pump. The activity of the electrogenic H+-pump was formulated in terms of the change in the free energy of ATP hydrolysis. The deviation of membrane potential from the H+ equilibrium potential induces a passive H+ flow. The passive inward H+ current may be coupled with Cl- uptake. The coupling rate of H+,Cl- co-transport was discussed. The membrane potential of mitochondria was electrochemically formulated in terms of oxidation-reduction H2/H+ half-cells spontaneously formed at the inner and outer boundaries of each trans-membrane electron-conducting pathway. The membrane potential formed by a pair of H2/H+ redox cells is pH-sensitive in its nature, but deviates from the H+ equilibrium potential to an extent that depends on the logarithm of the ratio of H2 concentrations at the inner and outer boundaries. The membrane potential of thylakoids is considered to be primarily due to the electromotive force of photocells embedded in the thylakoid membrane, as far as the anode and cathode of each photocell are in contact with the inner and outer solutions, respectively. The light-induced electronic current yields oxygen at the inner boundary and causes an increase in the H2 pool at the outer boundary of the electron-conducting pathway, which has no shunting plastoquinone chain between these two boundaries.
丽藻细胞的静息膜电位随H⁺平衡电位的变化而平行移动，但并不等于H⁺平衡电位。膜电位与H⁺平衡电位的偏差取决于生电H⁺泵排出H⁺的速率。生电H⁺泵的活性根据ATP水解自由能的变化来表示。膜电位与H⁺平衡电位的偏差会引发被动的H⁺流动。被动内向H⁺电流可能与Cl⁻摄取相偶联。讨论了H⁺、Cl⁻共转运的偶联速率。线粒体的膜电位根据在每个跨膜电子传导途径的内外边界自发形成的氧化还原H₂/H⁺半电池进行电化学表示。由一对H₂/H⁺氧化还原电池形成的膜电位本质上对pH敏感，但偏离H⁺平衡电位的程度取决于内外边界H₂浓度比的对数。类囊体的膜电位被认为主要归因于嵌入类囊体膜中的光电池的电动势，只要每个光电池的阳极和阴极分别与内外溶液接触。光诱导的电子电流在内边界产生氧气，并导致电子传导途径外边界的H₂池增加，在这两个边界之间没有分流的质体醌链。
