Redox-driven membrane-bound proton pumps

In recent years, remarkable progress has been made in our understanding of the structure and function of membrane-bound proton transporters at the molecular level. Perhaps the most challenging and complex of these molecular machines are the haem-copper oxidases. These enzymes are designed to activate the kinetically stable O-2 molecule, to prevent the release of potentially toxic oxygen intermediates and, at the same time, to harness the free energy from O-2 reduction by pumping protons across the membrane. So far, the mechanism of proton pumping has not been determined in any proton pump driven by reduction-oxidation reactions. Although this remains one of the key problems of molecular bioenergetics, recent developments have brought us to its core and closer to its solution.