Mechanism of Hen Egg White Lysozyme Adsorption on a Charged Solid Surface
Mechanism of Hen Egg White Lysozyme Adsorption on a Charged Solid Surface
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DOI：
10.1021/la102960m
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发表时间：
2010-10-19
期刊：
影响因子：
3.9
通讯作者：
Mulheran, Paul A.
中科院分区：
文献类型：
--
作者：
Kubiak-Ossowska, Karina;Mulheran, Paul A.
用原子分子动力学(MD)模拟方法研究了鸡蛋清溶菌酶(HEWL)在带负电的亲水表面的吸附机理。16个90 ns的轨迹提供了足够的数据，以便对吸附过程进行详细描述。已经确定了两个不同的吸附位置。主要的一个位于N，C-末端的蛋白面，由Arg128(关键的一个)组成，辅以Arg125、Arg5和Lys1；次要的是偶然使用的，只含有Arg68。这种蛋白质的吸附是由静电学驱动的，其中蛋白质偶极矩的取向决定了蛋白质运动的方向。蛋白质在表面的扩散范围取决于蛋白质侧链对地表水层的渗透。这是由带电表面的长程电场促进的，可以将极性侧链排列成垂直于表面。对中性离子表面吸附的模拟表明，表面水层没有这种穿透。因此，蛋白质的柔韧性被认为是一个重要的因素，而要吸附HeWL必须调整其结构。然而，在平坦的表面上，只需要轻微损失α-螺旋含量。吸附的HEWL分子在侧面和末端之间定向，其中蛋白质长轴(主要接近偶极矩)与表面之间的夹角在45度到90度之间变化。靶向突变的模拟证实了从这些研究中出现的情况。活性中心位于主吸附中心的对面，因此固定化HEWL的活性不应受表面相互作用的影响。我们的结果提供了一个详细的洞察吸附机制和蛋白质在表面的迁移率。这些知识将有助于正确解释实验结果以及设计新的实验和功能系统。
The mechanism of hen egg white lysozyme (HEWL) adsorption on a negatively charged, hydrophilic surface has been studied using atomistic molecular dynamics (MD) simulation. Sixteen 90 ns trajectories provide adequate data to allow a detailed description of the adsorption process to be formulated. Two distinct adsorption sites have been identified. The main one is located on the N,C-terminal protein face and comprises Arg128 (the crucial one), supplemented by Arg125, Arg5, and Lys1; the minor one is used accidentally and contains only Arg68. Adsorption of this protein is driven by electrostatics, where the orientation of the protein dipole moment defines the direction of protein movement. The diffusion range on the surface depends on protein side-chain penetration through the surface water layers. This is facilitated by the long-range electric field of the charged surface, which can align polar side chains to be perpendicular to the surface. A simulation of adsorption onto a neutral ionic surface shows no such surface water layer penetration. Therefore, protein flexibility is seen to be an important factor, and to adsorb the HEWL has to adjust its structure. Nevertheless, at a flat surface only a slight loss of alpha-helical content is required. The adsorbed HEWL molecule is oriented between side-on and end-on ways, where the angle between the protein long axis (which mostly approximates the dipole moment) and the surface varies between 45 degrees and 90 degrees. Simulations with targeted mutations confirm the picture that emerges from these studies. The active site is located on the opposite face to the main adsorption site; hence, the activity of the immobilized HEWL should not be affected by the surface interactions. Our results provide a detailed insight into the adsorption mechanism and protein mobility at the surface. This knowledge will aid the proper interpretation of experimental results and the design of new experiments and functional systems.