Temperature-induced spectral properties of chlorophyll a incorporated into egg-yolk lecithin liposomes and lipo-protein complexes.

The temperature-induced fluorescence changes of Chl a in the systems consisting of albumin-egg-yolk lecithin and only lecithin were studied. As plotted against temperature in liposomes the fluorescence intensity of Chl a has a maximum at approximately 35 degrees C. In CLP complexes the curve profile for the fluorescence intensity versus temperature is sharper and the maximum occurred at a lower temperature (25 degrees C). No fluorescence maxima for ANS in liposomes and for Chl a in isotropic solutions were found. The second derivative absorption spectra of the investigated lipid systems exhibited bands which were characteristic of monomeric Chl a. We suggested that in the temperature zone studied Chl a in vitro is embedded within lipid bilayer rather than attached to the proteins. The occurrence of the fluorescence intensity maximum of Chl a in liposomes and lipo-protein complexes is related to the effects: temperature quenching of the fluorescence, Chl a-lipid interaction.