QUANTITATIVE MEASUREMENTS OF MEMBRANE-POTENTIAL IN ESCHERICHIA-COLI
QUANTITATIVE MEASUREMENTS OF MEMBRANE-POTENTIAL IN ESCHERICHIA-COLI
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DOI：
10.1021/bi00556a026
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发表时间：
1980-01-01
期刊：
影响因子：
2.9
通讯作者：
KABACK, HR
中科院分区：
文献类型：
--
作者：
FELLE, H;PORTER, JS;KABACK, HR
利用E.大肠杆菌的生长诱导的6-amidinopenicillanic酸的存在下，膜电位测定2个完全独立的技术：直接与细胞内微电极和间接从稳态分布的[3 H]tetraphenylphosphonium。在各种条件下，这两种方法产生的值非常接近。使用这两种技术，膜电位在pH 5.0下约为-85 mV（内部负），在pH 8.0下约为-142 mV，在pH 5.0-7.0范围内的平均斜率为-22 mV/pH单位。从巨细胞制备的膜囊泡的平行研究进行单独使用四苯基磷分布作为膜电位的测量。与完整的巨细胞相比，囊泡表现出小得多的膜电位相对于细胞外pH的斜率（约-6 mV/pH单位）。这些亲脂性阳离子的分布研究提供了一个很好的衡量膜电位和讨论有关的计算H+/基板的质子对称系统在E。杆菌
By use of giant cells of E. coli induced by growth in the presence of 6-amidinopenicillanic acid, membrane potentials were measured by 2 completely independent techniques: directly with intracellular microelectrodes and indirectly from the steady-state distribution of [3H]tetraphenylphosphonium. Under a variety of conditions, the 2 methods yield values that agree very closely. With both techniques, the membrane potential approximates -85 mV (interior negative) at pH 5.0 and -142 mV at pH 8.0, with an average slope of -22 mV/pH unit over the range pH 5.0-7.0. A parallel study of membrane vesicles prepared from giant cells was undertaken using tetraphenylphosphonium distribution alone as a measure of membrane potential. The vesicles exhibited a much smaller slope of membrane potential vs. extracellular pH (about -6 mV/pH unit) than intact giant cells. Distribution studies with these lipophilic cations provide an excellent measure of membrane potential and are discussed in relation to calculations of H+/substrate stoichiometry for protonsymport systems in E. coli.