文章基本信息

标题：Phase composition of lipoprotein SM/cholesterol/PtdCho affects FA specificity of sPLA2s
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作者：Arnis Kuksis ; Waldemar Pruzanski
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2008
卷号：49
期号：10
页码：2161-2168
DOI：10.1194/jlr.M800167-JLR200
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：We have previously reported preferential release of polyunsaturated FAs during hydrolysis of lipoprotein phosphatidylcholine (PtdCho) by group X secretory phospholipase A₂ (sPLA₂) and preferential release of oligounsaturated FAs during hydrolysis of lipoprotein PtdCho by group V sPLA₂, but the mechanism of this selectivity has remained unknown. We now show that the rate and specificity of hydrolysis are affected by relative increases in endogenous SM and free cholesterol (FC) during the lipase digestion. The highest preference for arachidonate release from LDL and HDL by group X sPLA₂ was observed for residual SM/PtdCho molar ratio of 1.2 and 0.4, compared with the respective starting ratios of 0.4 and 0.2, as measured by liquid chromatography/electrospray ionization-mass spectrometry. Group V sPLA₂ showed preferential release of linoleate from LDL and HDL at SM/PtdCho ratio 1.5 and 0.6, respectively. We have attributed the change in FA specificity to segregation of molecular species of PtdCho and of sPLA₂s between disordered and ordered SM/FC/PtdCho lipid phases. The increases in SM and FC during digestion with group IIA sPLA₂ were more limited, and a preferential hydrolysis of any FAs was not observed. The significance of SM and FC SM and FC accumulation during sPLA₂ hydrolysis of lipoprotein PtdCho has been previously overlooked.