The stability and structure of cholesterol-rich codispersions of cholesterol and phosphatidylcholine.
The stability and structure of cholesterol-rich codispersions of cholesterol and phosphatidylcholine.
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DOI：
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发表时间：
1982-02
影响因子：
6.5
通讯作者：
J. J. Collins-J.;M. Phillips
中科院分区：
文献类型：
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作者：
J. J. Collins-J.;M. Phillips
为了研究富含胆固醇的磷脂酰胆碱（PC）分散体的结构和稳定性，通过超声处理将胆固醇/二棕榈酰磷脂酰胆碱（DPPC）混合物以4 +/-0.5/1至1/1的摩尔比分散在水中。这些分散体包含直径在200-1800 A范围内的脂质体和单层囊泡。当使用DPPC时，在20 ℃下这些颗粒中具有66 A重复距离的双层可以含有高达4 mol胆固醇/mol PC，并且使用蛋PC时约为该比例的一半。这些分散体是亚稳定的，因为在4或20 ℃下储存会导致囊泡的聚集和沉淀;此外，颗粒中胆固醇/PC摩尔比降低，并形成胆固醇一水合物晶体。胆固醇释放缓慢，含有超过等摩尔量胆固醇的PC分散体可以稳定数月。游离胆固醇的量通过差示扫描量热法由与在157 ℃下从近晶液晶转变为液体胆固醇相关的热测定。在温和混合的条件下，当混合物最初含有小于约3 mol胆固醇/mol DPPC时，胆固醇在DPPC双层中的最大溶解度为1.0 +/-0.1mol/mol PC。这与已发表的平衡相图一致，该平衡相图表明等摩尔PC/胆固醇双层在水中是稳定的。
In order to investigate the structure and stability of cholesterol-enriched dispersions of phosphatidylcholine (PC), cholesterol/dipalmitoyl phosphatidylcholine (DPPC) mixtures with molar ratios of 4 +/- 0.5/1 to 1/1 were dispersed in water by sonication. These dispersions comprise liposomes and unilamellar vesicles with diameters in the range 200-1800 A. The bilayers which have a repeat distance of 66 A in these particles at 20 degrees C can contain up to 4 mol cholesterol/mol PC when DPPC is used and about half this ratio with egg PC. these dispersions are metastable in that storage at either 4 or 20 degrees C leads to aggregation and precipitation of vesicles; in addition, there is a decrease in the cholesterol/PC molar ratio in the particles and formation of cholesterol monohydrate crystals. Cholesterol is released slowly and PC dispersions containing more than equimolar amounts of cholesterol can be stable for several months. The amount of free cholesterol was determined by differential scanning calorimetry from the heat associated with the transition at 157 degrees C from smectic liquid crystal to liquid cholesterol. Under conditions of gentle mixing, the maximum solubility of cholesterol in DPPC bilayers is 1.0 +/- 0.1 mol/mol PC when the mixture initially contains less than about 3 mol cholesterol/mol DPPC. This is consistent with published equilibrium phase diagrams which show that equimolar PC/cholesterol bilayers are stable in water.