FLUORESCENCE STUDY OF A DERIVATIZED DIACYLGLYCEROL INCORPORATED IN MODEL MEMBRANES

A fluorescence study of a diacylglycerol derivatized with the n-(7-nit robenz-2-oxa-1,3-diazol-4-yl) chromophore (NBD) was carried out. Fluor escence self-quenching was observed for this probe in lecithin model m embranes due to collisional interaction rather than to an aggregationa l behaviour of the probe. The efficient energy migration (R(0) = 28 An gstrom) of the NBD fluorophore was studied via the fluorescence depola rization upon increase of probe concentration in membranes, and the re sults are compared with a model where a random distribution of the pro bes is assumed. A surface location of the chromophore was concluded fo r the NBD derivative of diacylglycerol, both from the fluorescence par ameters and from the study of its fluorescence quenching by spin label probes. Very high lateral diffusion coefficients were obtained for th ese probes, both from the self-quenching (D = 2-6 x 10(-6) cm(2) s(-1) ) and from the spin probe quenching (D = 3.5 x 10(-6) cm(2) s(-1)) stu dies. A concomitant fluorescence study of the related probe NBD-phosph atidylcholine revealed that its photophysical behaviour is similar to the derivatized diacylglycerol.