New paradigm for ATP synthesis and consumption
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A central postulate of the chemiosmotic theory of ATP synthesis (Mitchell 1966) in mitochondria is the presence of a delocalized electrical potential of about 200 mV (Δφ) across the energy-transducing membrane between two bulk aqueous compartments. This Δφ forms the major component of the driving force for ATP synthesis, according to this theory.
Experimental techniques to measure this electrical potential difference can be classified into two categories. The first method is to use ions that are permeant to the inner mitochondrial membrane or to introduce non-physiological substances that are charged and membrane-permeant. By achieving transmembrane diffusion of these ions or substances, Δφ can be calculated using the assumption of equilibrium and the Nernst equation (Mitchell 1966). The second method is to employ microelectrodes to penetrate the inner mitochondrial membrane and make direct measurements of the potential across it (Tedeschi 1980). Each method has its own protagonists....