Protein Diffusion and Long-Term Adsorption States at Charged Solid Surfaces
Protein Diffusion and Long-Term Adsorption States at Charged Solid Surfaces
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DOI：
10.1021/la303323r
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发表时间：
2012-11-06
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.
采用全原子控制的分子动力学模拟方法研究了溶菌酶吸附在模型带电离子表面的扩散路径。模拟从现有的蛋白质吸附轨迹开始，其中已经发现一个特定的残基，N，C-末端面处的Arg 128，在将溶菌酶锚定到表面中起着关键作用[Langmuir 2010，26，15954-15965]。我们首先研究的蛋白质的解吸途径，通过拉Arg 128侧链远离表面在正常方向，其随后的再吸附，研究扩散途径之前，通过拉Arg 128侧链平行于表面。我们发现，该侧链的方向在扩散过程中起着决定性的作用。最初，它的取向垂直于表面，在吸附过程中在表面的静电场中对齐，但在再吸收后，它平行于表面，由于表面结构化水层的几何约束，无法返回到其原始取向。从这种替代吸附状态的扩散具有类似于0.9 eV的较低的能量势垒，与破坏氢键沿着的途径，在合理的协议从先前的实验观察溶菌酶表面聚类推断的障碍。这些结果表明，研究蛋白质扩散吸附的重要性，以充分了解蛋白质簇和膜的形成，功能化表面的未来发展的重要步骤。
The diffusion pathways of lysozyme adsorbed to a model charged ionic surface are studied using fully atomistic steered molecular dynamics simulation. The simulations start from existing protein adsorption trajectories, where it has been found that one particular residue, Arg128 at the N,C-terminal face, plays a crucial role in anchoring the lysozyme to the surface [Langmuir 2010, 26, 15954-15965]. We first investigate the desorption pathway for the protein by pulling the Arg128 side chain away from the surface in the normal direction, and its subsequent readsorption, before studying diffusion pathways by pulling the Arg128 side chain parallel to the surface. We find that the orientation of this side chain plays a decisive role in the diffusion process. Initially, it is oriented normal to the surface, aligning in the electrostatic field of the surface during the adsorption process, but after resorption it lies parallel to the surface, being unable to return to its original orientation due to geometric constraints arising from structured water layers at the surface. Diffusion from this alternative adsorption state has a lower energy barrier of similar to 0.9 eV, associated with breaking hydrogen bonds along the pathway, in reasonable agreement with the barrier inferred from previous experimental observation of lysozyme surface clustering. These results show the importance of studying protein diffusion alongside adsorption to gain full insight into the formation of protein clusters and films, essential steps in the future development of functionalized surfaces.