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标题：Interaction of pulmonary surfactant protein A with dipalmitoylphosphatidylcholine and cholesterol at the air/water interface
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作者：Shou-Hwa Yu ; Fred Possmayer
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：1998
卷号：39
期号：3
页码：555-568
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Interaction of pulmonary surfactant protein A (SP-A) with pure and binary mixed dipalmitoylphosphatidylcholine (DPPC) and cholesterol (3.5 wt%) at the air/saline, 1.5 m m CaCl₂ interface was investigated using a rhomboid surface balance at 37°C. Surface tension–area isotherms were measured to access the surface active properties of the monolayers. The organization of DPPC and cholesterol in DPPC and DPPC/cholesterol mixed monolayers with or without SP-A at equilibrium surface tension (≈23 mN/N) was revealed by autoradiographs of Langmuir-Blodgett (L-B) films deposited from [¹⁴C]DPPC or [¹⁴C]cholesterol-labeled monolayers. The results showed that SP-A can interact with the polar head groups of DPPC monolayers and aggregate DPPC molecules. SP-A decreased the surface area reduction required for DPPC monolayers to achieve near zero surface tension from 30 to 25% of the area at equilibrium. SP-A also reduced the collapse surface tension of pure cholesterol from 27 to 23 mN/m. DPPC and cholesterol formed homogeneous mixed monolayers when both were dissolved in the spreading solvent prior to spreading, while separate cholesterol-rich domains appeared when DPPC and cholesterol were spread successively. Cholesterol resisted squeeze-out from either mixed monolayer through compression. Although SP-A could not promote the squeeze-out of cholesterol from homogeneous mixed monolayers, it facilitated that of cholesterol domains especially when SP-A had first interacted with DPPC. These results indicate that pulmonary surfactant protein A facilitates the squeeze-out of cholesterol domains from mixed monolayers by condensing DPPC and limiting lateral interactions of DPPC with cholesterol domains.— Yu, S-H., and F. Possmayer. Interaction of pulmonary surfactant protein A with dipalmitoylphosphatidylcholine and cholesterol at the air/water interface. J. Lipid Res. 1998. 39: 555–568.
关键词：air/water interface ; dipalmitoylphosphatidylcholine ; monolayer ; cholesterol ; L-B film ; pulmonary surfactant ; surface tension ; surfactant-associated protein A