Conformation changes in bacteriorhodopsin photocycle studied by pump and probe tryptophan fluorescence decay

Recent photoselection measurements on bacteriorhodospin at high pH and high ionic strength showed a high change of the anisotropy factor in the ms region. If this is due to a conformation change in the moiety of retinal chromophore, one can expect that it is also reflected in the fluorescence decay of tryptophan residues in the close vicinity of the chromophore. Time resolved tryptophan fluorescence measurements were carried out at different stages of bacteriorhodospin photocycle by a pump and probe method. Early results indicate a correlation between the time constant of the faster phase of the fluorescence decay and the anisotropy factor.