title: Perturbation of phospholipid bilayers by DDT.
abstract: The localization of the effects of DDT (5-50 mol%) addition on the acyl chain dynamics in unilamellar vesicles of two phosphatidylcholines (DPPC and egg PC) has been investigated by steady-state fluorescence polarization of a series of n-(9-anthroyloxy) fatty acids (n = 2, 6, 9, 12 and 16) whose fluorophore is located at a graded series of depths from the surface to the centre of the bilayer. The results show that DDT is a fluidizer of DPPC and egg PC bilayers. The increase in microviscosity of DPPC bilayers at 23 degrees C begins at the centre of the bilayer (5 mol% DDT) and proceeds outward to the surface with increasing concentration of DDT (17 mol%). This pattern of effects is not evident in fluid bilayers of DPPC at 54 degrees C or egg PC at 23 degrees C. DDT (33 mol%) also lowers the phase transition temperature of DPPC bilayers by approximately 2 Cdeg. DDT (17 mol%) had no effect on the mean excited fluorescence life-time of 2-AP and 12-AS in DPPC, DOPC and egg PC bilayers. No quenching of 2-AP fluorescence was evident.
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000378:metabolism; D003634:DDT / Q000494:pharmacology*; D005227:Fatty Acids / Q000032:analysis; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D013696:Temperature
chemical_list: D005227:Fatty Acids; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010743:Phospholipids; D015060:1,2-Dipalmitoylphosphatidylcholine; D003634:DDT; C017251:1,2-oleoylphosphatidylcholine