Photolysis of Phenanthrenequinone in Phospholipid Vesicles

Abstract

Phospholipid vesicles of saturated and unsaturated phosphatidylcholines have been prepared with phenanthrenequinone incorporated into the hydrocarbon region of the lipid bilayer. Blue or ultraviolet light exposure of these vesicles causes a loss of quinone absorbance and the corresponding formation of new absorbance bands due to addition products. In vesicles composed of unsaturated phospholipids, cycloaddition is preferred over R--H addition. The quant urn yield for quinone disappearance is -0.25 in vesicles which contain unsaturated phospholipids and decreases to 0.08 when the photolysis is conducted below the lipid characteristic temperature.