Angle resolved fluorescence depolarisation of 1,6-diphenyl-1,3,5 hexatriene (DPH) in unsaturated digalactosyl diacylglycerol (DGDG) lipid bilayers.

The orientational ordering and dynamics of DPH molecules embedded in macroscopically ordered bilayers of the unsaturated galactolipid digalactosyl diacylglycerol (DGDG) were studied by angle-resolved fluorescence depolarisation at room temperature. The depolarisation ratios exhibited a weaker angular dependence than those observed for DPH incorporated in multi-bilayers of saturated lecithins above their phase transition. The results reflect the differences in the modes of reorientational motion of the DPH molecules in these systems while a similar orientational order is found. It is suggested that DPH molecules in bilayers of DGDG cannot be considered to possess an effective cylindrical symmetry in contrast to DPH in bilayers of saturated lecithins.