Studies of membrane heterogeneity using fluorescence associative techniques

Abstract

Fluorescence spectra, decay times and emission anisotropy are capable of providing important information regarding the interaction of probes with biological macromolecules. Combinations of different fluorescence parameters can provide information about heterogeneity of liposomes or biological membranes and about the character of excited-state interactions of the fluorescence probe. Decay-associated spectra (DAS) or anisotropy decay associated spectra (ADAS) can be used to resolve heterogeneous species. These methods have been applied to the study of both pyrene and a pyrene methyl cholesterol adduct (PMC) with dimyristoyl-lecithin vesicles (DML). The data indicate microheterogeneity in the distribution of the probes above the phase transition. Anisotropy decay-associated spectra (ADAS) have been used to study diphenylhexatriene (DPH) in dipalmitoyl-lecithin (DPL) and dimyristoyl-lecithin (DML) vesicles. The results indicate that DPH inhabits more than one rotational environment in the liposome preparations used.