Letellier L, Shechter E
Eur J Biochem. 1979 Dec 17;102(2):441-7. doi: 10.1111/j.1432-1033.1979.tb04259.x.
The fluorescence response of a positively charged cyanine dye: 3,3'-dimethylindodicarbocyanine iodide can be specifically related to the generation in Escherichia coli cells and E. coli membrane vesicles of an electrical membrane potential induced either by substrate oxidation or by an artificially imposed potassium diffusion gradient. The energy-dependent quenching of the dye fluorescence correlates well with the known effect on delta phi of: oxidation of various energy sources, external pH and solute accumulation. Thus, in the vesicles, the fluorescence quenching of the dye increases from succinate to D-lactate, to ascorbate/phenazine methosulfate and parallels the increasing ability of these electron donors to generate a delta phi. In the vesicles, delta phi is only weakly dependent on external pH, whereas in the cells, delta phi increases with increasing external pH. Lactose accumulation in the vesicles results in the partial utilization of delta phi. A calibration of the dye fluorescence in terms of delta phi has been determined using valinomycin-induced potassium diffusion potential.
带正电荷的花青染料（3,3'-二甲基吲哚二碳菁碘化物）的荧光响应，可能与大肠杆菌细胞及大肠杆菌膜囊泡中因底物氧化或人为施加的钾扩散梯度所诱导产生的跨膜电位密切相关。染料荧光的能量依赖性猝灭，与各种能源氧化、外部pH值及溶质积累对膜电位差（Δφ）的已知影响高度相关。因此，在膜囊泡中，染料的荧光猝灭程度从琥珀酸盐到D-乳酸盐再到抗坏血酸/吩嗪硫酸甲酯逐渐增加，且与这些电子供体产生膜电位差的能力增强趋势一致。在膜囊泡中，膜电位差仅微弱依赖于外部pH值，而在细胞中，膜电位差随外部pH值升高而增加。膜囊泡中乳糖的积累会导致膜电位差的部分消耗。利用缬氨霉素诱导的钾扩散电位，已确定了基于膜电位差的染料荧光校准。
