Photocycle of 13-cis-retinal in bacteriorhodopsin caused by destruction to the cooperative effect of purple membrane

The steady absorption and kinetic changes of M₄₁₂ intermediate of the light- and dark-adapted bacteriorhodopsin (BR) solubilized by different concentrated Triton X-100 were investigated. The results indicated that the cooperative effect existing within the trimeric BR of native purple membrane (PM) was damaged in the system containing the surfactant since the component and structure of the bilayer lipid membrane in PM varied due to the solubilization of partial PM lipids by Triton X-100. The destruction to the cooperative effect of BR ultimately caused 13-cis-retinal of the dark-adapted BR to take part in BR photocycle and also to generate the deprotonated M₄₁₂ intermediate. Project supported by the key and major projects from the Chinese Academy of Sciences (Grant Nos. Kj951-A1-501-05 and Kj952-S1-03)