Hamaide F, Kushner D J, Sprott G D
J Bacteriol. 1983 Nov;156(2):537-44. doi: 10.1128/jb.156.2.537-544.1983.
The influence of pH on the proton motive force of Vibrio costicola was determined by measuring the distributions of triphenylmethylphosphonium cation (membrane potential, delta psi) and either dimethyloxazolidinedione or methylamine (osmotic component, delta pH). As the pH of the medium was adjusted from 5.7 to 9.0, the proton motive force steadily decreased from about 170 to 100 mV. This decline occurred, despite a large increase in the membrane potential to its maximum value at pH 9.0, because of the loss of the pH gradient (inside alkaline). The cytoplasm and medium were of equal pH at 7.5; membrane permeability properties were lost at the pH extremes of 5.0 and 9.5. Protonophores and monensin prevented the net efflux of protons normally found when an oxygen pulse was given to an anaerobic cell suspension. A Na+/H+ antiport activity was measured for both Na+ influx and efflux and was shown to be dissipated by protonophores and monensin. These results strongly favor the concept that respiratory energy is used for proton efflux and that the resulting proton motive force may be converted to a sodium motive force through Na+/H+ antiport (driven by delta psi). A role for antiport activity in pH regulation of the cytosol can also explain the broad pH range for optimal growth, extending to the alkaline extreme of pH 9.0.
通过测量三苯甲基鏻阳离子（膜电位，Δψ）以及二甲基恶唑烷二酮或甲胺（渗透成分，ΔpH）的分布，确定了pH对栖热栖热弧菌质子动力势的影响。随着培养基的pH从5.7调节至9.0，质子动力势从约170 mV稳步下降至100 mV。尽管膜电位在pH 9.0时大幅增加至最大值，但由于pH梯度的丧失（内部呈碱性），仍出现了这种下降。细胞质和培养基在pH 7.5时pH相等；在pH 5.0和9.5的极端值时，膜通透性特性丧失。质子载体和莫能菌素可防止在向厌氧细胞悬液施加氧脉冲时通常出现的质子净外流。对Na⁺的流入和流出均测量了Na⁺/H⁺反向转运活性，结果表明其可被质子载体和莫能菌素消除。这些结果有力地支持了这样一种观点，即呼吸能量用于质子外流，并且由此产生的质子动力势可通过Na⁺/H⁺反向转运（由Δψ驱动）转化为钠动力势。反向转运活性在细胞质pH调节中的作用也可以解释最佳生长的广泛pH范围，该范围可延伸至pH 9.0的碱性极端值。
