Nichols W W
Regional Public Health Laboratory, John Radcliffe Hospital, Oxford, U.K.
Biochim Biophys Acta. 1987;895(1):11-23. doi: 10.1016/s0304-4173(87)80014-9.
This review examines two mechanisms, the channel and the uniport, proposed to explain the rapid, energy-dependent (EDP-II) phase of transport of dihydrostreptomycin (and streptomycin) across the bacterial cytoplasmic membrane. Bioenergetic and kinetic predictions are made from these two mechanisms and compared with available experimental data. Both the above mechanisms would be expected to lead to reversible transport kinetics, and to observable uptake of dihydrostreptomycin by respiring cytoplasmic membrane vesicles. However, transport is kinetically irreversible and is not observed in membrane vesicles (although the membrane vesicle findings need further confirmation), so the author rejects the proposed channel and uniport mechanisms. A possible mechanism of dihydrostreptomycin transport that would be consistent with the above experimental data, would be one in which a chemical reaction occurred as an obligatory part of the translocation cycle. Such a mechanism could be classified as primary translocation. The author emphasizes that this hypothesis is put forward to stimulate further experimental testing; it is not proposed to be a definitive explanation of the mechanism of energy-dependent dihydrostreptomycin transport.
本综述探讨了两种机制，即通道机制和单向转运机制，这两种机制被提出来用以解释二氢链霉素（和链霉素）跨细菌细胞质膜的快速、能量依赖（EDP-II）转运阶段。从这两种机制出发进行了生物能量学和动力学预测，并与现有的实验数据进行了比较。上述两种机制预计都会导致可逆的转运动力学，并且会观察到呼吸性细胞质膜囊泡对二氢链霉素的摄取。然而，转运动力学是不可逆的，并且在膜囊泡中未观察到转运现象（尽管膜囊泡的研究结果需要进一步证实），因此作者否定了所提出的通道机制和单向转运机制。一种与上述实验数据相符的二氢链霉素转运的可能机制，是一种化学反应作为转运循环必不可少的一部分而发生的机制。这种机制可归类为初级转运。作者强调，提出这一假设是为了激发进一步的实验测试；它并非旨在对能量依赖的二氢链霉素转运机制给出确定性解释。
