Friedberg I, Kaback H R
J Bacteriol. 1980 May;142(2):651-8. doi: 10.1128/jb.142.2.651-658.1980.
Using the distribution of weak acids to measure the pH gradient (delta pH; interior alkaline) and the distribution of the lipophilic cation [3H]tetraphenylphosphonium+ to monitor the membrane potential (delta psi; interior negative), we studied the electrochemical gradient or protons (delta mu- H+) across the membrane of Micrococcus lysodeikticus cells and plasma membrane vesicles. With reduced phenazine methosulfate as electron donor, intact cells exhibited a relatively constant delta mu- H+ (interior negative and alkaline) of -193 mV to -223 mV from pH 5.5 to pH 8.5. On the other hand, in membrane vesicles under the same conditions, delta mu- H+ decreased from a maximum value of -166 mV at pH 5.5 to -107 mV at pH 8.0 and above. This difference is related to a differential effect of external pH on the components of delta mu- H+. In intact cells, delta pH decreased from about -86 mV (i.e., 1.4 units) at pH 5.5 to zero at pH 7.8 and above, and the decreases in delta pH was accompanied by a reciprocal increase in delta psi from -110 mV at pH 5.5 to -211 mV at pH 8.0 and above. In membrane vesicles, the decrease in delta pH with increasing external pH was similar to that described for intact cells; however, delta psi increased from -82 mV at pH 5.5 to only -107 mV at pH 8.0 and above.
利用弱酸的分布来测量pH梯度（ΔpH；内部呈碱性），并利用亲脂性阳离子[³H]四苯基鏻⁺的分布来监测膜电位（Δψ；内部呈负电），我们研究了溶壁微球菌细胞和质膜囊泡膜上质子的电化学梯度（Δμ-H⁺）。以还原型吩嗪硫酸甲酯作为电子供体，完整细胞在pH 5.5至pH 8.5范围内表现出相对恒定的Δμ-H⁺（内部呈负电且碱性），为-193 mV至-223 mV。另一方面，在相同条件下的膜囊泡中，Δμ-H⁺从pH 5.5时的最大值-166 mV降至pH 8.0及以上时的-107 mV。这种差异与外部pH对Δμ-H⁺各组分的不同影响有关。在完整细胞中，ΔpH从pH 5.5时的约-86 mV（即1.4个单位）降至pH 7.8及以上时的零，并且ΔpH的降低伴随着Δψ从pH 5.5时的-110 mV相应增加至pH 8.0及以上时的-211 mV。在膜囊泡中，随着外部pH升高，ΔpH的降低与完整细胞中描述的情况相似；然而，Δψ从pH 5.5时的-82 mV仅增加至pH 8.0及以上时的-107 mV。
