Interaction of α-tocopherol with model human high-density lipoproteins
Interaction of α-tocopherol with model human high-density lipoproteins
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DOI：
10.1016/s0006-3495(98)77734-3
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发表时间：
1998-12-01
影响因子：
3.4
通讯作者：
Pownall, HJ
中科院分区：
文献类型：
--
作者：
Massey, JB;Pownall, HJ
采用物理化学方法研究了α -生育酚对人载脂蛋白a- 1和二肉豆烯酰基磷脂酰胆碱组成的模型高密度脂蛋白（hdl）性质的影响。α -生育酚的本征荧光及其对探测脂质碳氢区域的1,6-二苯基-1,3,5-己三烯和探测脂质表面的4-庚烷基-7-羟基香豆素的荧光偏振的影响表明，α -生育酚位于脂质-水界面。相对于胆固醇，脂质表面的-生育酚在物理化学上几乎是惰性的。α -生育酚掺入hdl后，仅引起颗粒大小的适度增加，转变温度没有变化，脂质极性和脂质-脂质相互作用也几乎没有变化。此外，α -生育酚对亲脂酶卵磷脂的动力学参数的影响可以忽略不计：胆固醇酰基转移酶与磷脂酰胆碱表面结合并形成胆固醇酯。然而，α -生育酚对载脂蛋白a- l与二肉豆蔻酰基磷脂酰胆碱的结合率有显著的抑制作用，这一过程是通过将蛋白质插入脂质表面的预先形成的缺陷而发生的。有人提出，α -生育酚通过插入脂质表面的缺陷来抑制载脂蛋白a- 1与二肉豆蔻酰基磷脂酰胆碱的结合率，从而减少载脂蛋白a- 1插入位点的大小和/或数量。
The effects of alpha-tocopherol on the properties of model high-density lipoproteins (HDLs), composed of human apolipoprotein A-l and dimyristoylphosphatidylcholine, were investigated by physicochemical methods. The intrinsic fluorescence of alpha-tocopherol and its effects on the polarization of fluorescence of 1,6-diphenyl-1,3,5-hexatriene, which probes the hydrocarbon region of the lipids, and 4-heptadecyl-7-hydroxycoumarin, which is a probe of lipid surfaces, suggest that alpha-tocopherol is located at the lipid-water interface. Relative to cholesterol, alpha-tocopherol in lipid surfaces is virtually inert physicochemically. Incorporation of alpha-tocopherol into HDLs induces only a modest increase in particle size, no change in the transition temperature, and little change in lipid polarity and lipid-lipid interactions. Moreover, alpha-tocopherol has only a negligible effect on the kinetic parameters of the lipophilic enzyme lecithin:cholesterol acyltransferase, which binds to phosphatidylcholine surfaces and forms cholesteryl esters. However, alpha-tocopherol has a dramatic inhibitory effect on the rate of association of apolipoprotein A-l with dimyristoylphosphatidylcholine, a process that occurs through the insertion of the protein into preformed defects in the lipid surface. It is proposed that alpha-tocopherol inhibits the rate of association of apolipoprotein A-I with dimyristoylphosphatidylcholine by inserting into defects within the lipid surface, thereby reducing the size and/or number of sites for insertion of apolipoprotein A-l.