FLUORESCENCE QUENCHING BY METAL-IONS IN LIPID BILAYERS

Fluorescence quenching of perylene by Co2+ and Ni2+ ions has been inve stigated both below and above the phase transition temperature in smal l unilamellar DPPC vesicles. Classic Forster type energy transfer was observed for perylene quenched by Co2+ ions below the phase transition when the effects of donor-donor energy transfer are taken into accoun t. In the liquid crystalline phase a simple diffusion theory incorpora ting energy transfer was found to model the system well. For quenching by Ni2+ ions both above and below the phase transition temperature in lipid bilayers and in glycerol the data did not follow classic Forste r type energy transfer but indicated that an additional quenching mech anism was present. A mechanism other than Forster behaviour was also o bserved for the quenching by Cr3+ ions in glycerol.