ELECTROCHEMICAL GRADIENT OF PROTONS AND ITS RELATIONSHIP TO ACTIVE-TRANSPORT IN ESCHERICHIA-COLI MEMBRANE-VESICLES
ELECTROCHEMICAL GRADIENT OF PROTONS AND ITS RELATIONSHIP TO ACTIVE-TRANSPORT IN ESCHERICHIA-COLI MEMBRANE-VESICLES
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DOI：
10.1073/pnas.73.6.1892
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发表时间：
1976-01-01
影响因子：
11.1
通讯作者：
KABACK, HR
中科院分区：
文献类型：
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作者：
RAMOS, S;SCHULDINER, S;KABACK, HR
从大肠杆菌分离的膜小泡在适当的条件下产生2个pH单位的跨膜质子梯度，当用流动透析测定时。使用弱酸的分布来测量质子梯度(ΔpH)和亲脂性阳离子三苯基甲基膦的分布来测量跨膜的电势(Δ...PSI)，显示了小泡产生APPRX的电化学质子梯度(Δ...H+)。-180 mV，pH 5.5，有抗坏血酸和吩嗪甲硫酸盐存在，其主要成分是APPRX的pH差值。-110 mV。随着外部pH的增加，ΔpH降低，在pH>req时达到0。7.5，而.DELTA..PSI.保持.apprx。-75 mV，内部pH保持在pH 7.5。各种电子给体驱动传输的能力与它们产生ΔHIVIN·H+的能力相关。PH差值和差值差值可以在呋喃霉素和黑霉素的存在下相互变化。化学渗透现象在主动转运中的作用被强烈地指出。
Membrane vesicles isolated from E. coli generate a trans-membrane proton gradient of 2 pH units under appropriate conditions when assayed by flow dialysis. Using the distribution of weak acids to measure the proton gradient (.DELTA.pH) and the distribution of the lipophilic cation triphenylmethylphosphonium to measure the electrical potential across the membrane (.DELTA..PSI.), the vesicles are shown to generate an electrochemical proton gradient (.DELTA..hivin..mu.H+) of .apprx. -180 mV at pH 5.5 in the presence of ascorbate and phenazine methosulfate, the major component of which is a .DELTA.pH of .apprx. -110 mV. As external pH is increased, .DELTA.pH decreases, reaching 0 at pH .gtoreq. 7.5, while .DELTA..PSI. remains .apprx. -75 mV and internal pH remains at pH 7.5. The ability of various electron donors to drive transport is correlated with their ability to generate .DELTA..hivin..mu.H+. .DELTA.pH and .DELTA..PSI. can be varied reciprocally in the presence of valinomycin and nigericin. The role of chemiosmotic phenomena in active transport is strongly indicated.