In Mitchell's chemiosmotic theory, membrane potential Δψ was given as the electric potential difference across the membrane. However, its physical origin for membrane potential Δψ was not well explained. Using the Lee proton electrostatic localization model with a newly formulated equation for protonic motive force (pmf) that takes electrostatically localized protons into account, membrane potential has now been better understood as the voltage difference contributed by the localized surface charge density ([H-+L] + nΣ i=1 [M(i+)L]) at the liquid-membrane interface as in an electrostatically localized protons/cations-membrane-anions capacitor. That is, the origin of membrane potential Δψ is now better understood as the electrostatic formation of the localized surface charge density that is the sum of the electrostatically localized proton concentration [H+L ] and the localized non-proton cations density nΣ(i=1) [M(i+)L] at the liquid membrane interface. The total localized surface charge density equals to the ideal localized proton population density [H+L]0 before the cation-proton exchange process; since the cation proton exchange process does not change the total localized charges density, neither does it change to the membrane potential Δψ. The localized proton concentration [H+L] represents the dominant component, which accounts about 78% of the total localized surface charge density at the cation-proton exchange equilibrium state in animal mitochondria. Liquid water as a protonic conductor may play a significant role in the biological activities of membrane potential formation and utilization.
Original Publication Citation
Lee, J. W. (2019). Electrostatically localized proton bioenergetics: Better understanding membrane potential. Heliyon, 5(7), e01961. doi:10.1016/j.heliyon.2019.e01961
Lee, James Weifu, "Electrostatically Localized Proton Bioenergetics: Better Understanding Membrane Potential" (2019). Chemistry & Biochemistry Faculty Publications. 174.