Antunes-Madeira M do C, Madeira V M
Centro de Biologia Celular, Departamento de Zoologia, Coimbra Codex, Portugal.
Biochim Biophys Acta. 1993 Jun 18;1149(1):86-92. doi: 10.1016/0005-2736(93)90028-x.
2,2-Bis(p-chlorophenyl)-1,1-dichloroethylene (DDE) interaction with model and native membranes was studied by means of fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), probing the bilayer core, and by intramolecular excimerization of 1,3-di(1-pyrenyl) propane (Py(3)Py), probing the outer regions of the bilayer. In the gel phase of DMPC bilayers, DDE induces concentration-dependent fluidizing effects into the hydrophobic core, but no effects are detected in the outer regions of the membrane, as evaluated by DPH and Py(3)Py, respectively. Regarding the fluid phase, DDE has no apparent effect on the bilayer center, but it induces a limited ordering effect on the outer regions. Similar effects are described for bilayers of DPPC and DSPC. Unlike DPH, Py(3)Py is very sensitive to DPPC and DSPC pretransitions, not abolished by DDE (50 microM), as opposite to the effects observed with lindane (Antunes-Madeira, M.C., Almeida, L.M. and Madeira, V.M.C. (1990) Biochim. Biophys. Acta 1022, 110-114), but similar to those observed with DDT (Antunes-Madeira, M.C., Almeida, L.M. and Madeira, V.M.C. (1991) Pestic. Sci. 33, 347-357). DDE inhibits to some extent the cholesterol-induced ordering in DMPC bilayers and high cholesterol concentrations (> or = 30 mol%) do not prevent DDE interaction, as evaluated by DPH. On the other hand, the effects of DDE reported by Py(3)Py depend on temperature and cholesterol contents of DMPC bilayers. For cholesterol levels ranging from 10 to 50 mol% and temperatures below the phase transition of DMPC, Py(3)Py fails to detect any significant effect. Nevertheless, above the phase transition, Py(3)Py detects either ordering effects of DDE at low cholesterol contents (< 30 mol%) or fluidizing effects at high cholesterol levels (> or = 30 mol%). The results in native membranes correlate reasonably with those obtained in models of synthetic lipids. Thus, DPH does not detect any apparent effect of DDE in relatively fluid native membranes of sarcoplasmic reticulum, but detects moderate disordering effects in membranes of brain microsomes and erythrocytes, i.e., membranes with high cholesterol. On the other hand, Py(3)Py reports ordering effects of DDE in fluid membranes of sarcoplasmic reticulum, an effect similar to that observed in fluid systems of synthetic lipids without or with low cholesterol. Additionally, as described for models, Py(3)Py detects disordering effects of DDE in cholesterol rich membranes, namely, brain microsomes.
通过1,6 - 二苯基 - 1,3,5 - 己三烯（DPH）的荧光偏振研究了2,2 - 双（对氯苯基）-1,1 - 二氯乙烯（DDE）与模型膜和天然膜的相互作用，该方法用于探测双层核心，同时通过1,3 - 二（1 - 芘基）丙烷（Py(3)Py）的分子内激基缔合物形成来研究，该方法用于探测双层的外部区域。在二肉豆蔻酰磷脂酰胆碱（DMPC）双层的凝胶相中，DDE在疏水核心中诱导浓度依赖性的流化效应，但通过DPH和Py(3)Py分别评估发现，在膜的外部区域未检测到影响。对于液相，DDE对双层中心没有明显影响，但它在外部区域诱导有限的有序化效应。对于二棕榈酰磷脂酰胆碱（DPPC）和二硬脂酰磷脂酰胆碱（DSPC）双层也描述了类似的效应。与DPH不同，Py(3)Py对DPPC和DSPC的预转变非常敏感，不会被50微摩尔的DDE消除，这与林丹观察到的效应相反（Antunes - Madeira, M.C., Almeida, L.M.和Madeira, V.M.C. (1990) Biochim. Biophys. Acta 1022, 110 - 114），但与滴滴涕观察到的效应相似（Antunes - Madeira, M.C., Almeida, L.M.和Madeira, V.M.C. (1991) Pestic. Sci. 33, 347 - 357）。通过DPH评估发现，DDE在一定程度上抑制了胆固醇诱导的DMPC双层中的有序化，并且高胆固醇浓度（≥30摩尔%）并不能阻止DDE的相互作用。另一方面，Py(3)Py报道的DDE效应取决于DMPC双层的温度和胆固醇含量。对于胆固醇水平在10%至50%摩尔之间且温度低于DMPC相变温度的情况，Py(3)Py未能检测到任何显著影响。然而，在相变温度以上，Py(3)Py在低胆固醇含量（<30%摩尔）时检测到DDE的有序化效应，在高胆固醇水平（≥30%摩尔）时检测到流化效应。天然膜中的结果与在合成脂质模型中获得的结果合理相关。因此，DPH在相对流动性较好的肌质网天然膜中未检测到DDE的任何明显影响，但在脑微粒体和红细胞膜（即高胆固醇膜）中检测到中度的无序化效应。另一方面，Py(3)Py报道了DDE在肌质网流动性膜中的有序化效应，这与在不含或含低胆固醇的合成脂质流动性系统中观察到的效应相似。此外，如模型中所述，Py(3)Py在富含胆固醇膜（即脑微粒体）中检测到DDE的无序化效应。
