Time-resolved titrations of ASP-85 in acteriorhodopsin: The multicomponent kinetic mechanism

The Asp-85 residue is important to the function of bacteriorhodopsin (bR), acting as a light-driven proton pump. Time-resolved titrations of Asp-85 were undertaken over a broad range of pH and cation concentrations. pH and cation jumps induced the Purple-Blue transition in both directions. It was found that binding/unbinding of metal cations is not rate-determining in Asp-85 titration.