Old and new data, new issues: the mitochondrial DeltaPsi.
New and old data pertinent to the electrochemical potentials across the inner mitochondrial membrane are reviewed with the intent of reconciling the various findings in the light of new perspectives provided by more recent knowledge. A careful scrutiny of old data permits ruling out the presence of a significant metabolically dependent electrical membrane potential. Recent technological advances make it possible to test the proposed alternatives. These proposals recast the original idea, and the possible mechanisms that are emerging also invoke a protonmotive force. Our conclusions that DeltaPsi is not involved in oxidative-phosphorylation finds parallel observations in Halobacterium halobium [H. Michel, D. Oesterhelt, Electrochemical proton gradient across the cell membrane of Halobacterium halobium: comparison of the light-induced increase with the increase of intracellular adenosine triphosphate under steady-state illumination, Biochemistry 19 (1980) 4615-4619] and thylakoid vesicles [D.R. Ort, R.A. Dilley, N.E. Good, Photophosphorylation as a function of illumination time II. Effects of permeant buffers, Biochim. Biophys. Acta 449 (1976) 108-129] in which light-induced ATP synthesis occurs in the absence of an apparent DeltaPsi or DeltapH, suggesting the presence of mechanisms similar to the one proposed for mitochondria.
Tedeschi
Henry
H
Department of Biological Sciences, State University of New York at Albany, Albany, NY 12222, USA. tedeschi@albany.edu
D004734:Energy Metabolism / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D051336:Mitochondrial Membranes / Q000378:metabolism / Q000502:physiology*; D008956:Models, Chemical; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D018892:Proton-Motive Force / Q000502:physiology*; D014634:Valinomycin / Q000378:metabolism
D014634:Valinomycin; D011188:Potassium