Membrane potential generation

Membrane potential and pH gradient are always determined separately. Since a membrane potential is a delocalized parameter for a given membrane, it follows that the membrane potential generated by the translocation of protons across the membrane will be felt by all ions distributed across the membrane. If an electrical uniport pathway exists for one of these ions, then it will tend to come to an equilibrium when its electrochemical potential gradient is zero ... 

EC Hurt, N Gabellini, Y Shahak, W Lockau and G Hauska (1983) Extra proton translocation and membrane potential generation universal properties ofcytochrom cdbef complexes reconstituted into liposomes. Arch Biochem Biophys 225 879-885... 

The recent experiments mainly support the above proposal. Most detailed data come from ingenious experiments in which the membrane potential generated by the enzyme upon single electron injection is measured with microsecond resolution. For example, in the F to O transition, the data show one short protonic phase followed by another slow and large in amplitude protonic phase [27]. These two kinetic phases correspond to two proton transfer reactions of the above model [28]. 

Time-resolved measurement of the membrane potential generated by the enzyme upon single-electron injection has been one of the most fruitful techniques in the studies of CcO [17]. However, the quantitative interpretation of such experiments requires a computational input. We have recently started developing a theory and the necessary computational tools for interpretation of potentiometry experiments [28,37]. It appears that not only geometry of the enzyme determines the amplitudes... 

Holoubek, A. Vecer, J. Opekarova, M. Sigler, K. Ratiometric fluorescence measurements of membrane potential generated by yeast plasma membrane H -ATPase reconstituted into vesicles. Biochim. Biophys. Acta, Biomembr. 2003, 1609, 71-79. 

Bandell, M., Ansanay, V, Rachidi, N., et al. (1997) Membrane potential-generating malate (MleP) and citrate (CitP) transporters of lactic acid bacteria are homologous proteins. Substrate specificity of the 2-hydroxycarboxylate transporter family. 7 Bi oZ Chem 272,18140-18146. 

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