Novel fluorescence-photochrome labeling method in the study of biomembrane dynamics

A novel photochrome-fluorescence method (PFLM) based on monitoring fluorescence parameters and kinetics of photochrome photoisomerization of para-substituted stilbenes (PSS) has been proposed. It was shown that PSS exhibits fluorescence characteristics which are similar to ones of typical membrane fluorescence probes such as diphenylhexatriene (DPH). A study of kinetics of PSS trans-cis and cis-trans photoisomerization makes it possible to estimate, under certain conditions, the rotational correlation time of the stilbene fragments in the excited state of PSS for the fixed angle 180°. In viscous media this process is a rate-determining stage. Taken together, the both techniques, fluorescence and photochrome, make it possible to establish a detailed mechanism and measure quantititive parameters of stilbene probe (PSS) mobility in a membrane. The PFLM was applied to the study of E. coli membrane dynamics.