EFFECT OF ORGANOTIN COMPOUNDS ON MEMBRANE-LIPIDS - FLUORESCENCE SPECTROSCOPY STUDIES

The temperature dependence of 1,6-diphenyl-1,3,5-hexatriene (DPH) and (4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) fluoresce nce anisotropy has been studied to investigate the influence of mono-n -butyltin chloride (MBTC), di-n-butyltin chloride (DBTC) and tri-n-phe nyl chloride (TPTC) on the physicochemical state of dipalmitoyl phosph atidylcholine, Below the lipid chain melting transition (T-m), fluores cence anisotropy values of DPH and TMA-DPH are increased by the presen ce of the organotins, without important modifications of the phase tra nsition temperature. A possible difference in localization of the orga notin compounds is suggested by the differential effect of the probes. It is suggested that there is localization in the hydrophobic core of the bilayer for TPTC, and at the head-group level for DBTC, and a hom ogeneous distribution in the bilayer for MBTC. Similar studies have be en performed in liposomal suspensions of cardiolipin, phosphatidylseri ne and egg phosphatidylcholine.