Hellingwerf K J, Friedberg I, Lolkema J S, Michels P A, Konings W N
J Bacteriol. 1982 Jun;150(3):1183-91. doi: 10.1128/jb.150.3.1183-1191.1982.
Within the scope of a study on the effects of changes in medium composition on the proton motive force in Rhodopseudomonas sphaeroides, the energy coupling of sodium, phosphate, and potassium (rubidium) transport was investigated. Sodium was transported via an electroneutral exchange system against protons. The system functioned optimally at pH 8 and was inactive below pH 7. The driving force for the phosphate transport varied with the external pH. At pH 8, Pi transport was dependent exclusively on delta psi (transmembrane electrical potential), whereas at pH 6 only the delta pH (transmembrane pH gradient) component of the proton motive force was a driving force. Potassium (rubidium) transport was facilitated by a transport system which catalyzed the electrogenic transfer of potassium (rubidium) ions. However, in several aspects the properties of this transport system were different from those of a simple electrogenic potassium ionophore such as valinomycin: (i) accumulated potassium leaked very slowly out of cells in the dark; and (ii) the transport system displayed a threshold in the delta psi, below which potassium (rubidium) transport did not occur.
在一项关于培养基成分变化对球形红假单胞菌质子动力影响的研究范围内，对钠、磷酸盐和钾（铷）转运的能量偶联进行了研究。钠通过一个电中性交换系统逆质子转运。该系统在pH 8时功能最佳，在pH 7以下无活性。磷酸盐转运的驱动力随外部pH值而变化。在pH 8时，Pi转运仅依赖于Δψ（跨膜电势），而在pH 6时，质子动力的ΔpH（跨膜pH梯度）成分是唯一的驱动力。钾（铷）的转运由一个催化钾（铷）离子电生转移的转运系统促进。然而，该转运系统在几个方面与简单的电生钾离子载体（如缬氨霉素）不同：（i）积累的钾在黑暗中从细胞中泄漏得非常缓慢；（ii）该转运系统在Δψ中表现出一个阈值，低于该阈值钾（铷）转运不会发生。
