Photochemical reactions of bacteriorhodopsin in Triton X-100 solution studied by low temperature spectrophotometry

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Abstract
The photochemical reaction of purple membrane solubilized with Triton X-100 (T-BR) was investigated by low temperature spectrophotometry. The batho- and meta-intermediates of T-BR were observed to resemble bacteriorhodopsin in native purple membrane. Two photoproducts characteristic of the T-BR system were found, which were named the "490-nm complex" and the "380-nm complex". The 490-nm complex was in thermal equilibrium with T-BR in the dark. Cooling T-BR to low temperature favoured the 490-nm complex, which was photoinsensitive. On the other hand, the 380-nm complex was produced by warming the batho-intermediate and reverted to the original T-BR. The meta-intermediate of T-BR may possibly be in thermal equilibrium with the 380-nm complex. On the basis of the above results, the possible role of the membrane structure was discussed