Proton translocation by bacteriorhodopsin and heme-copper oxidases.

Proton translocation is the means by which free energy is conserved from oxygen reduction by the respiratory heme-copper oxidases and from sunlight by bacteriorhodopsin. Three-dimensional structures at atomic resolution of both proteins have aided functional studies of the proton translocation mechanism. A comparison reveals common structural and functional features that may be unique to the primary proton pumps in biology.