Gutknecht J
Department of Physiology, Duke University, Beaufort, North Carolina 28516.
J Bioenerg Biomembr. 1987 Oct;19(5):427-42. doi: 10.1007/BF00770028.
The proton/hydroxide (H+/OH-) permeability of phospholipid bilayer membranes at neutral pH is at least five orders of magnitude higher than the alkali or halide ion permeability, but the mechanism(s) of H+/OH- transport are unknown. This review describes the characteristics of H+/OH- permeability and conductance through several types of planar phospholipid bilayer membranes. At pH 7, the H+/OH- conductances (GH/OH) range from 2-6 nS cm-2, corresponding to net H+/OH- permeabilities of (0.4-1.7) X 10(-5) cm sec-1. Inhibitors of GH/OH include serum albumin, phloretin, glycerol, and low pH. Enhancers of GH/OH include chlorodecane, fatty acids, gramicidin, and voltages greater than 80 mV. Water permeability and GH/OH are not correlated. The characteristics of GH/OH in fatty acid (weak acid) containing membranes are qualitatively similar to the controls in at least eight different respects. The characteristics of GH/OH in gramicidin (water wire) containing membranes are qualitatively different from the controls in at least four different respects. Thus, the simplest explanation for the data is that GH/OH in unmodified bilayers is due primarily to weakly acidic contaminants which act as proton carriers at physiological pH. However, at low pH or in the presence of inhibitors, a residual GH/OH remains which may be due to water wires, "hydrated defects," or other mechanisms.
在中性pH条件下，磷脂双分子层膜对质子/氢氧根离子（H⁺/OH⁻）的通透性比碱金属离子或卤离子的通透性至少高五个数量级，但H⁺/OH⁻的转运机制尚不清楚。本综述描述了通过几种类型的平面磷脂双分子层膜的H⁺/OH⁻通透性和电导率的特征。在pH 7时，H⁺/OH⁻电导率（GH/OH）范围为2 - 6 nS cm⁻²，对应于（0.4 - 1.7）×10⁻⁵ cm s⁻¹的净H⁺/OH⁻通透性。GH/OH的抑制剂包括血清白蛋白、根皮素、甘油和低pH。GH/OH的增强剂包括氯代癸烷、脂肪酸、短杆菌肽和大于80 mV的电压。水通透性与GH/OH不相关。含脂肪酸（弱酸）的膜中GH/OH的特征在至少八个不同方面与对照在质量上相似。含短杆菌肽（水通道）的膜中GH/OH的特征在至少四个不同方面与对照在质量上不同。因此，对这些数据最简单的解释是，未修饰双分子层中的GH/OH主要归因于弱酸性污染物，这些污染物在生理pH下充当质子载体。然而，在低pH或存在抑制剂的情况下，仍存在残余的GH/OH，这可能归因于水通道、“水合缺陷”或其他机制。
