I will discuss correlated transport of electrons and protons in cytochrome c oxidase, the terminal enzyme in the respiratory electron transport chain of aerobic organisms. This enzyme catalyses the reduction of atmospheric oxygen to water in our cells, and converts free energy of oxygen reduction for the creation of the membrane proton gradient, by pumping protons across the membrane. The proton gradient subsequently drives the synthesis of ATP. The details of the mechanism of this redox-driven proton pump are unknown. Computer simulations and theoretical modeling point to a possible mechanism of this biological molecular electronic device, in which electronics is coupled to proton translocation.

1. D.M. Popovic and A. A. Stuchebrukhov, Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating, FEBS Lett. 2004. 2. A.A. Stuchebrukhov, Electron transfer reactions coupled to proton translocation. Cytochrome oxidase, proton pumps, and biological energy transduction. J. Theor. Comp. Chem. 1, 91-118, 2003. 3. D.M. Medvedev, E.S. Medvedev, A.A. Stuchebrukhov, Analysis of the kinetics of the membrane potential generated by cytochrome oxidase upon single electron injection. BBA 2005, in press.