Abstract: The decay rate of bacteriorhodopsin photocycle intermediate M412 in purple membrane LB film treated by ions and temperature was studied. The results showed that the decay rate turned fast with increaseing temperature. The decay of M₄₁₂s was inhibited by La³⁺ at low concentration, but by K⁺ at higher concentration. The decay of M₄₁₂s was accelerated by K⁺ and Ca²⁺ except La³⁺. The change of pH affected the decay rate of M412, When pH value reached 11, the decay rate of M₄₁₂s was much slower than that of normal pH value.

Key words: purple membrane, bacteriorhodopsin, photocycle, proton pump, LB film.