Lipid binding by fragments of apolipoprotein C-III-1 obtained by thrombin cleavage.
Lipid binding by fragments of apolipoprotein C-III-1 obtained by thrombin cleavage.
复制标题
通过凝血酶裂解获得的载脂蛋白 C-III-1 片段与脂质结合。
DOI：
10.1021/bi00644a004
复制
发表时间：
1977
期刊：
影响因子：
2.9
通讯作者：
A. Gotto
中科院分区：
文献类型：
--
作者：
J. Sparrow;H. Pownall;F. J. Hsu;L. Blumenthal;A. R. Culwell;A. Gotto
我们使用凝血酶将载脂蛋白C-III-1切割成两个片段，分别构成残基1-40 （apoLP-C-III-A）和41-79 （apoLP-C-III-B）。这些片段与二肉豆醇酰和1-棕榈酰-2-油基磷脂酰胆碱的脂质结合特性已经用圆二色性和固有色氨酸荧光光谱测定。用氯化铯的密度梯度对肽-磷脂混合物进行分馏。在DMPC缺失和存在的情况下，ApoLP-C-III-A结构紊乱，未分离到大量肽磷脂复合物。ApoLP-C-III-B在圆二色光谱中表现出构象变化和固有色氨酸荧光光谱的移位。在氯化铯梯度中进行超离心，得到密度在1.10和1.18之间的肽-磷脂复合物。脂质与蛋白质的摩尔比为12:1。这些研究结果和对apoLP-C-III的空间填充模型的检验表明，包含非极性面和极性面的两性α螺旋是血浆载脂蛋白结合磷脂的基本结构单元。这些结果也提供了直接的证据，证明非极性面的疏水性在脂质结合中是重要的，因为残基1-40的非极性面比残基41-79的非极性面疏水性要小得多。
We have used thrombin to cleave apolipoprotein C-III-1 into two fragments constituting residues 1-40 (apoLP-C-III-A) and 41-79 (apoLP-C-III-B). The lipid binding properties of these fragments with dimyristoyl- and 1-palmitoyl-2-oleoylphosphatidylcholines have been determined using circular dichroic and intrinsic tryptophan fluorescence spectroscopy. The peptide-phospholipid mixtures were fractionated by density gradients of cesium chloride. ApoLP-C-III-A showed disordered structure in the absence and presence of DMPC and no significant amount of peptide-phospholipid complex was isolated. ApoLP-C-III-B showed conformational changes in the circular dichroic spectrum and a shift in the intrinsic tryptophan fluorescence spectrum. Ultracentrifugation in cesium chloride gradients yielded peptide-phospholipid complexes isolated between density 1.10 and 1.18. The molar ratio of lipid to protein was 12:1. The results of these studies and the examination of space filling models of apoLP-C-III provide evidence that an amphipathic alpha helix which contains a nonpolar face and a polar face is the basic structural unit for binding of phospholipid by the plasma apolipoproteins. These results also provide direct evidence that the hydrophobicity of the nonpolar face is important in lipid binding since the nonpolar face of residues 1-40 is considerably less hydrophobic than the nonpolar face of residues 41-79.