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首页> 美国卫生研究院文献>Biophysical Journal >Protein-induced vertical lipid dislocation in a model membrane system: spin-label relaxation studies on avidin-biotinylphosphatidylethanolamine interactions.
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Protein-induced vertical lipid dislocation in a model membrane system: spin-label relaxation studies on avidin-biotinylphosphatidylethanolamine interactions.

机译：蛋白质在模型膜系统中引起的垂直脂质脱位：自旋标记弛豫研究抗生物素蛋白-生物素磷脂酰乙醇胺的相互作用。

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The change in vertical location of spin-labeled N-biotinyl phosphatidylethanolamine in fluid-phase dimyristoyl phosphatidylcholine bilayer membranes, on binding avidin to the biotinyl headgroup, has been investigated by progressive saturation electron spin resonance measurements. Spin-labeled phospholipids were present at a concentration of 1 mol%, relative to total membrane lipids. For avidin-bound N-biotinyl phosphatidylethanolamine spin-labeled on the 8 C atom of the sn-2 chain, the relaxation enhancement induced by 30 mM Ni2+ ions confined to the aqueous phase was 2.5 times that induced by saturating molecular oxygen, which is preferentially concentrated in the hydrophobic core of the membrane. For phosphatidylcholine also spin-labeled at the 8 position of the sn-2 chain, this ratio was reversed: the relaxation enhancement by Ni2+ ions was half that induced by molecular oxygen. In the absence of avidin, the enhancement by either relaxant was the same for both spin-labeled phospholipids. For a double-labeled system, in which both N-biotinyl phosphatidylethanolamine and phosphatidylcholine were spin-labeled on the 12 C atom of the sn-2 chain, the relaxation rate in the absence of avidin was greater than that predicted from linear additivity of the corresponding singly labeled systems, because of mutual spin-spin interactions between the two labeled lipid species. On binding of avidin to the N-biotinyl phosphatidylethanolamine, this relaxation enhancement by mutual spin-spin interaction was very much decreased. These results indicate that, on binding of avidin to the lipid headgroup, N-biotinyl phosphatidylethanolamine is lifted vertically within the membrane, relative to the phosphatidylcholine host lipids. The specific binding of avidin to N-biotinyl phosphatidylethanolamine parallels the liftase activity proposed for activator proteins associated with the action of certain gangliosidases.
机译：已经通过逐步饱和电子自旋共振测量研究了在亲和素结合到生物素基头基上时，液相二甲豆基磷脂酰胆碱双层膜中自旋标记的N-生物素基磷脂酰乙醇胺的垂直位置的变化。旋转标记的磷脂相对于总膜脂的浓度为1 mol％。对于在sn-2链的8 C原子上自旋标记的抗生物素蛋白结合的N-生物素基磷脂酰乙醇胺，限制在水相中的30 mM Ni2 +离子引起的弛豫增强是饱和分子氧引起的弛豫增强的2.5倍，这优先浓缩在膜的疏水核中。对于同样在sn-2链的8位旋转标记的磷脂酰胆碱，该比例也可以相反：Ni2 +离子的弛豫增强是分子氧诱导的弛豫增强的一半。在不存在抗生物素蛋白的情况下，两种旋转标记的磷脂通过任一松弛剂的增强作用均相同。对于双标记系统，其中N-生物素基磷脂酰乙醇胺和磷脂酰胆碱都被旋转标记在sn-2链的12 C原子上，在不存在抗生物素蛋白的情况下，其弛豫速率大于根据线性加成法预测的弛豫速率。相应的单个标记的系统，因为两个标记的脂质物种之间存在相互自旋-旋转相互作用。在抗生物素蛋白与N-生物素基磷脂酰乙醇胺结合时，通过相互自旋-自旋相互作用的这种弛豫增强被大大降低。这些结果表明，在抗生物素蛋白结合至脂质头基上时，相对于磷脂酰胆碱宿主脂质，N-生物素基磷脂酰乙醇胺在膜内被垂直提升。抗生物素蛋白与N-生物素基磷脂酰乙醇胺的特异性结合与针对某些神经节苷酶的作用的激活蛋白提出的提升酶活性平行。

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