Membrane-induced conformational change in human apolipoprotein H.
Membrane-induced conformational change in human apolipoprotein H.
复制标题
人载脂蛋白 H 膜诱导的构象变化。
作者：
Shaopeng Wang;Yu Tong Sun;Sen‐fang Sui
载脂蛋白H（Apo H）与脂质膜的相互作用被认为是该蛋白发挥生物学功能的基本机制。先前的报告已证明 Apo H 只能与含有阴离子磷脂的膜相互作用。在这里，我们通过 CD 光谱法使用两种不同的模型系统研究膜诱导的 Apo H 构象变化：含阴离子磷脂的脂质体 [例如 1, 2-二肉豆蔻酰基-sn-甘油-3-磷酸甘油 (DMPG) 和心磷脂]，以及中等低 pH 下的水/甲醇混合物，模拟膜表面附近的微物理化学环境。研究发现，Apo H 在与含有阴离子磷脂的脂质体相互作用时发生显着的构象变化。为了与含有 DMPG 的脂质体相互作用，二级结构中的 α 螺旋增加了 6.8%；然而，在含有心磷脂的脂质体中，α-螺旋增加了 12.6%，β-折叠减少了 9%。 Apo H 中类似的构象变化可以通过用适当的水/甲醇混合物处理来诱导。结果表明，Apo H 与膜的结合与蛋白质二级结构的某些构象变化相关。
The interaction of apolipoprotein H (Apo H) with lipid membrane has been considered to be a basic mechanism for the biological function of the protein. Previous reports have demonstrated that Apo H can interact only with membranes containing anionic phospholipids. Here we study the membrane-induced conformational change of Apo H by CD spectroscopy with two different model systems: anionic-phospholipid-containing liposomes [such as 1, 2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) and cardiolipin], and the water/methanol mixtures at moderately low pH, which mimic the micro-physicochemical environment near the membrane surface. It is found that Apo H undergoes a remarkable conformational change on interaction with liposomes containing anionic phospholipid. To interact with liposomes containing DMPG, there is a 6.8% increase in alpha-helix in the secondary structures; in liposomes containing cardiolipin, however, there is a 12.6% increase in alpha-helix and a 9% decrease in beta-sheet. The similar conformation change in Apo H can be induced by treatment with an appropriate mixture of water/methanol. The results indicate that the association of Apo H with membrane is correlated with a certain conformational change in the secondary structure of the protein.