Thermal behavior of synthetic sphingomyelin-cholesterol dispersions.
Thermal behavior of synthetic sphingomyelin-cholesterol dispersions.
复制标题
合成鞘磷脂-胆固醇分散体的热行为。
DOI：
10.1021/bi00577a042
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发表时间：
1979
期刊：
影响因子：
2.9
通讯作者：
T. E. Thompson
中科院分区：
文献类型：
--
作者：
T. Estep;D. Mountcastle;Y. Barenholz;R. Biltonen;T. E. Thompson
用高灵敏度差示扫描量热法研究了棕榈酰鞘磷脂-胆固醇和二十四烷基鞘磷脂-胆固醇混合物的水分散液的热致行为。当小于25摩尔%的胆固醇与鞘磷脂混合时，量热吸热由尖锐和宽组分组成。锐分量焓变随着胆固醇摩尔百分比的增加而减小，外推的零焓点为25至30摩尔%。与棕榈酰鞘磷脂，尖锐的组分的最大热容量的温度随着胆固醇含量的增加单调下降，而lignocerylsphingomyelin尖锐的组分的最大值保持不变，直到超过20摩尔%的甾醇是存在的。对于两种鞘磷脂，宽组分焓变在10和20摩尔%胆固醇之间在3- 4千卡/摩尔处最大，并且随着胆固醇比率从该范围增加或减少而降低。结果进行了比较，从以前的研究二棕榈酰磷脂酰胆碱-胆固醇的混合物，并解释为证据的共存的胆固醇丰富和胆固醇贫乏的阶段。
The thermotropic behavior of aqueous dispersions of palmitoylsphingomyelin-cholesterol and lignoceryl-sphingomyelin-cholesterol mixtures has been examined by high-sensitivity differential scanning calorimetry. When less than 25 mol % cholesterol is mixed with either sphingomyelin, the calorimetric endotherm is composed of a sharp and a broad component. The sharp-component enthalpy change decreases as the mole percent cholesterol increases with the extrapolated zero enthalpy point being 25 to 30 mol %. With palmitoylsphingomyelin, the temperature of maximum heat capacity of the sharp component decreases monotonically with increasing cholesterol content, while the lignocerylsphingomyelin sharp-component maximum remains constant until more than 20 mol % sterol is present. The broad-component enthalpy change maximizes at 3--4 kcal/mol between 10 and 20 mol % cholesterol and decreases as the ratio of cholesterol is increased or decreased from this range for both sphingomyelins. The results are compared with those from a previous study on dipalmitoylphosphatidylcholine-cholesterol mixtures and are interpreted as evidence for the coexistence of cholesterol-rich and cholesterol-poor phases.