title: Ion-transport chain of cytochrome oxidase: the two chain-direct coupling principle of energy coupling.
abstract: Cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) couples the aerobic oxidation of ferrocytochrome c to the cyclical transport of monovalent cations or to the active transport of monovalent and divalent cations. This transport capability is mediated by an intracomplex ion-transport chain of two protein-bound molecules of cardiolipin per molecule of cytochrome oxidase. Cardiolipin in a two-phase system shows the identical ionophoric pattern as does the cytochrome oxidase coupled system. A molecular model of the cardiolipin chain suggests the possibility of a cage-like structure through which cations can be transferred from phosphate group to phosphate group. The ion-transport chain and the electron-transport chain are anchored to the same set of subunits (I+IV); the close proximity of the two chains argues for the direct coupling of electron and cation flow. The ion-transport chain of cytochrome oxidase provides an introduction to the molecular mechanisms by which ions are moved across membranes in energy-coupling systems.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001693:Biological Transport, Active; D002308:Cardiolipins / Q000378:metabolism; D002414:Cations, Monovalent / Q000378:metabolism; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007477:Ions; D008958:Models, Molecular
chemical_list: D000596:Amino Acids; D002308:Cardiolipins; D002414:Cations, Monovalent; D007477:Ions; D003576:Electron Transport Complex IV