Experimental Demonstration of Localized Excess Protons at a WaterMembrane Interface

Haitham A Saeed,James W Lee

doi:10.4172/2167-7662.1000127

Abstract

The widespread Mitchellian proton motive force equation has recently been revised with the proton-electrostatics localization hypothesis, which, for the first time, successfully elucidates the 30-year longstanding energetic conundrum of ATP synthesis in alkalophilic bacteria. To demonstrate the fundamental behavior of localized protons in a pure water-membrane-water system in relation to the newly derived pmf equation, excess protons and excess hydroxyl anions were generated by utilizing an i?½open-circuiti?½ water-electrolysis system and their distributions were tested using a proton-sensing aluminum membrane. The proton-sensing film placed at the membrane-water interface displayed dramatic localized proton activity while that placed into the bulk water phase showed no excess proton activity during the entire experiment. These observations clearly match with the prediction from the proton-electrostatics localization hypothesis that excess protons do not stay in water bulk phase; they localize at the water-membrane interface in a manner similar to the behavior of excess electrons in a conductor. This finding has significance not only in the science of bioenergetics but also in the fundamental understanding for the importance of water to life in serving as a proton conductor for energy transduction in living organisms.

Highlights

Peter Mitchell’s work on his chemiosmotic theory [1,2,3] won the 1978 Nobel prize in chemistry and his bioenergetics equation since was introduced into many textbooks [4,5,6]
We report our recent experimental study in which the distribution of localized excess protons at a water-membrane interface was demonstrated for the first time
According to the proton-electrostatics localization hypothesis, the free excess protons in the anode water body would not stay in the bulk liquid phase; they would localize to the water-membrane (Teflon) interface in the anode (P) chamber and attract the excess hydroxyl ions of the cathode water body to the NI site at the other side of the membrane, forming an “excess anions-membrane-excess protons” capacitor-like system

Summary

Introduction

Peter Mitchell’s work on his chemiosmotic theory [1,2,3] won the 1978 Nobel prize in chemistry and his bioenergetics (proton motive force) equation since was introduced into many textbooks [4,5,6]. Where C1 and C2 are the proton concentrations on the two sides of the membrane, Z is the charge on a proton (1 for a proton), F is the Faraday’s constant, ∆Ψ electrical potential difference across the membrane, R is the gas constant, and T is the absolute temperature. This Mitchellian equation (1), sometimes, is written as the equation for the proton motive force (pmf) ∆p that drives the protons through the ATP synthase: pmf (∆p) = –∆μ H + / F = ∆ψ – 2.3RT / F × ∆pH (2). Biochemists can understand the biological energy transduction processes far better than before the era of the chemiosmotic theory [8]

Methods

Results

Conclusion