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Fluorescence quenching techniques have been used extensively in recent years to examine reaction rates and the compartmentalization of components in lipid micelles and membranes. Steady-state fluorescence methods are frequently employed in such studies but the interpretation of the resulting Stern-Volmer plots is often hampered by uncertainties regarding the mode of association of the quencher with the lipid structure and the nature of the quenching mechanism. This paper presents a method for simulating steady-state Stern-Volmer plots in two phase systems, and shows how the forms of such plots are influenced by the type of association of the quencher with the membrane or micelle (partition and/or binding) and by the type of quenching mechanism (dynamic and/or static). Comparisons of simulated plots with experimental data must take into account the possible combinations of quencher association(s) and quenching mechanism(s). The methods presented are applicable to synthetic and natural membranes and provide a basis for comparing the quenching of fluorescent molecules in biological membranes of differing composition.

The fluorescence behaviour of a series of n-(9-anthroyloxy) fatty acids has been studied in saturated hydrocarbon solvents of increasing viscosity and solvents of increasing polarity. Fluorescence quenching experiments in these solvents and in micelles of sodium lauryl sulphate show that the probes locate at a graded series of depths in the micelle. The spectral characteristics of emission from the probes indicate an increasing polarity gradient from the core to the surface of the micelle.

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