Model role for bacteriorhodopsin for solar energy utilization by primordial organisms.

Enzymes similar in function to contemporary bacteriorhodopsin could have been active in primordial living organisms for the utilization of solar energy to produce ATP. The energy-conversion system, which depends on a light-driven proton pump, is enzymatically simple, insensitive to cyanide inhibition and functional under highly lipid conditions in an anaerobic atmosphere.