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标题：Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol
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作者：John M. Kauffman ; Philip W. Westerman ; Martin C. Carey 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2000
卷号：41
期号：6
页码：991-1003
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：We used an automated Langmuir-Pockels surface balance to characterize the air–water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl- sn -3-glycero-phosphocholine (POPC). Pressure–area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22–26 Å²/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH. In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 Å²/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydroxycholesterols expanded POPC monolayers at molar ratios —Kauffman, J. M., P. W. Westerman, and M. C. Carey. Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol. J. Lipid Res. 2000. 41: 991–1003.
关键词：phosphatidylcholine ; surface potential ; condensation ; isotherm ; orientation ; surface balance ; spectroscopic imaging