Fluorescence study on the domain formation of <Emphasis Type="Italic">N</Emphasis>-dodecanoyl-<Emphasis Type="SmallCaps">l</Emphasis>-tryptophan within a liposome membrane

The aggregation behavior of N-dodecanoyl-l-tryptophan within a liposome membrane was investigated by fluorescence spectroscopy. Liposomes with a mean diameter of 100 nm, formed from either 1-2-dilauroyl-sn-glycero-3-phosphocholine, 1-2-myristoyl-sn-glycero-3-phosphocholine, or 1-2-palmitoyl-sn-glycero-3-phosphocholine, were used. Fluorescence measurements indicate that the sodium salt of N-dodecanoyl-l-tryptophan forms domains with the liposome membranes below the main phase transition temperature, T _m. Above T _m, the molecules are homogeneously dispersed in the liquid crystalline state of the membranes.