According to the chemiosmotic hypothesis of oxidative and photo synthetic phosphorylation proposed by Mitchell (refs 1-4), the linkage between electron transport and phosphorylation occurs not because of hypothetical energy-rich chemical intermediaries as in the orthodox view, but because oxido-reduction and adenosine triphosphate (ATP) hydrolysis are each separately associated with the net translocation of a certain number of electrons in one direction and the net translocation of the same number of hydrogen atoms in the opposite direction across a relatively ion-, acid-, and base-impermeable coupling membrane (see also ref. 5).