Mitochondrial oxidative phosphorylation and respiratory chain: review

Basic events concerning oxidative phosphorylation, i.e. the synthesis of ATP at the expense of respired oxygen at the level of mitochondria are described. Our knowledge concerning the functioning of respiratory chain, its structure, organization and topology inside the inner membrane of mitochondria has considerably improved in recent years. A central question--how does the respiratory chain cooperate with ATP-synthetase, also embedded in the inner membrane, to bring about the oxidative phosphorylation of ADP to ATP--has been one of the most challenging and difficult problems in biochemical research. The chemiosmotic hypothesis proposed by the British biochemist Peter Mitchell appears best in describing the basic events of the recovery of the redox energy liberated along the respiratory chain to synthesize ATP through a membrane process. Moreover the chemiosmotic hypothesis is not restricted to mitochondrial oxidative phosphorylation but appears to provide a general explanation to the synthesis of ATP in all transducing membranes: inner mitochondrial membrane, bacterial plasma membrane, thylakoid membranes in chloroplasts of green plants.