Nonuniform lateral distribution of transmembrane deltapH in a coupling membrane as related to its curvature

Abstract

The possibility is analyzed that the pH of the water space localized inside the invagination of a membrane can differ from the pH of the external bulk buffer outside the invagination. The proton flow responsible for decreased pH values inside mitochondrial cristae and membrane invaginations of cyanobacteria has been calculated. If deltapsi (electric potential difference) inside and outside the invaginations is the same, there may exist a lateral microheterogeneity of transmembrane deltapH, and hence deltamu-H+. It seems that the invagination is a kind of buffer for accumulating deltamu-H+ in membrane systems. In eutrified waters (pH > 9) and also under the conditions of a sudden decrease or increase of light, or of a respiratory substrate of O2, ATP synthesis should proceed in the invaginated rather than in the flat regions of a membrane.