Is arginine charged in a membrane?
Is arginine charged in a membrane?
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DOI：
10.1529/biophysj.107.121566
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发表时间：
2008-01-15
影响因子：
3.4
通讯作者：
Allen, Toby W.
中科院分区：
文献类型：
--
作者：
Li, Libo;Vorobyov, Igor;Allen, Toby W.
带电荷的氨基酸在蛋白质的结构和功能中扮演着无数重要的角色。然而，当这些侧链与膜接触时，我们并不完全了解它们的行为。这一点在最近的电压门控离子通道活动模型和基于转位基因的实验中得到了强调，这些实验表明，将这些侧链暴露在脂质中的惩罚很小，这与膜生物物理学中的主流观点相反。在这里，我们使用侧链模拟以及跨膜螺旋模型来确定质子化状态和位置对膜上暴露的精氨酸(Arg)残基的自由能的影响。我们观察到带电状态和中性状态都有很高的自由能垒。由于膜变形对质子化形式的稳定影响，Arg侧链经历了pK(A)位移
'' Charged '' amino acids play countless important roles in protein structure and function. Yet when these side chains come into contact with membranes we do not fully understand their behavior. This is highlighted by a recent model of voltage-gated ion channel activity and translocon-based experiments that suggest small penalties to expose these side chains to lipids, opposing the prevailing view in membrane biophysics. Here we employ a side chain analog as well as a transmembrane helix model to determine the free energy as a function of protonation state and position for a lipid-exposed arginine (Arg) residue across a membrane. We observe high free energy barriers for both the charged and neutral states. Due to the stabilizing influence of membrane deformations for the protonated form, the Arg side chain experiences a pK(a) shift of