Evans R W
Department of Epidemiology, GSPH, University of Pittsburgh, PA 15261, USA.
Chem Phys Lipids. 1995 Nov 17;78(2):163-75. doi: 10.1016/0009-3084(95)02495-5.
Surface viscosities of phospholipid/steroid mixtures at the air-water interface were measured by means of an oscillating pendulum. Phospholipids studied included 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC); 1,2-dipalmitoyl-sn-glycero-3-phosphodimethylethanolamine (DPPDME); 1,2-dipalmitoyl-sn-glycero-3-phosphomonomethylethanolamine (DPPMME); 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE); 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DPPG); 1-palmitoyl-2-elaidyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-linelaidyl-sn-glycero-3-phosphocholine. Each saturated phospholipid was studied in the presence of cholesterol, DPPC was also investigated in the presence of 5-androsten-3beta-ol; cholestanol; 5-cholestene;5alpha-cholesten-3beta-ol methyl ether; coprostanol; 7,(5alpha)-cholesten-3beta-ol; desmosterol; epicholestanol; lanosterol and lophenol. The surface viscosities of the trans-unsaturated phosphatidylcholines (PC) were undetectable by this method and in this respect they resembled cis- unsaturated PC. The surface viscosities of saturated phospholipids were very high but were reduced by low concentrations of steroids. Interpretation of the results for DPPC/cholesterol mixtures indicates that DPPC functions at the air-water interface as a one-dimensional linear aggregate. At 50 mN/m and 22 degrees C the average structure contains approximately 300 DPPC molecules. DPPDME acts similarly but DPPMME, DPPE and DPPG differ from DPPC in their response to cholesterol. All of the steroids examined except 5-androsten-3beta-ol and the lanosterol mixture paralleled cholesterol in their interaction with DPPC an indication that phospholipid/steroid interactions modifying surface viscosity have less stringent requirements for the steroid structure than interactions measured as condensation in surface area.
通过振荡摆测量了磷脂/类固醇混合物在气-水界面的表面粘度。所研究的磷脂包括1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）；1,2-二棕榈酰-sn-甘油-3-磷酸二甲基乙醇胺（DPPDME）；1,2-二棕榈酰-sn-甘油-3-磷酸单甲基乙醇胺（DPPMME）；1,2-二棕榈酰-sn-甘油-3-磷酸乙醇胺（DPPE）；1,2-二棕榈酰-sn-甘油-3-[磷酸-rac-(1-甘油)]（DPPG）；1-棕榈酰-2-反式油酰-sn-甘油-3-磷酸胆碱和1-棕榈酰-2-反式亚油酸-sn-甘油-3-磷酸胆碱。每种饱和磷脂都在胆固醇存在的情况下进行了研究，DPPC还在5-雄甾烯-3β-醇、胆甾烷醇、5-胆甾烯；5α-胆甾烯-3β-醇甲基醚、粪甾烷醇、(5α)-胆甾烯-3β-醇、去氢胆固醇、表胆甾烷醇、羊毛甾醇和洛酚存在的情况下进行了研究。反式不饱和磷脂酰胆碱（PC）的表面粘度用这种方法无法检测到，在这方面它们与顺式不饱和PC相似。饱和磷脂的表面粘度非常高，但低浓度的类固醇会使其降低。对DPPC/胆固醇混合物结果的解释表明，DPPC在气-水界面作为一维线性聚集体起作用。在50 mN/m和22℃时，平均结构包含约300个DPPC分子。DPPDME的作用类似，但DPPMME、DPPE和DPPG在对胆固醇的反应上与DPPC不同。除5-雄甾烯-3β-醇和羊毛甾醇混合物外，所有检测的类固醇在与DPPC的相互作用上都与胆固醇相似，这表明修饰表面粘度的磷脂/类固醇相互作用对类固醇结构的要求比对表面积缩合测量的相互作用要求更低。
