Investigation on the interactions of peptides in the assembly of liposome and peptide by fluorescence.

The peptide-lipid and the peptide-peptide interactions of hydrophobic linear dipeptides containing tryptophan in liposome were investigated by fluorescence. The linear dipeptides were buried into the hydrophobic region of liposome to induce blue-shift of the fluorescence. With the addition of various anthracene derivatives to liposome, the energy transfer from tryptophan to anthryl group took place, which increased as the temperature decreased below the phase-transition temperature of the membrane. This phenomenon was explained in terms of the phase separation of the membrane, in which crystalline regions without the probes and the domains containing high concentrations of probes are intermixed. The energy-transfer efficiency was larger in the case of peptide acceptors than lipid acceptors. This suggests the presence of special interactions between donor peptide and acceptor peptide.