Molecular insight into protein conformational transition in hydrophobic charge induction chromatography: a molecular dynamics simulation.
Molecular insight into protein conformational transition in hydrophobic charge induction chromatography: a molecular dynamics simulation.
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DOI：
10.1021/jp809754k
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
Lin Zhang;Guofeng Zhao;Y. Sun
中科院分区：
文献类型：
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作者：
Lin Zhang;Guofeng Zhao;Y. Sun
疏水电荷感应色谱（HCIC）是一种结合了吸附中的疏水相互作用和洗脱中的静电斥力的吸附色谱。该方法已成功应用于抗体及其他蛋白质的分离纯化。然而，人们对蛋白质构象转变和吸附剂孔内的动态过程知之甚少。在本研究中，建立了一个孔隙模型来代表由基质和固定化 HCIC 配体组成的真实多孔吸附剂。通过对吸附剂孔中 46 珠 β 桶粗粒模型蛋白质的分子动力学模拟，显示了 HCIC 孔中的蛋白质吸附、解吸和构象转变及其对分离性能的影响。在达到稳定吸附之前，观察到蛋白质位置和方向的重复调整。一旦蛋白质被吸附，解折叠和重折叠之间就存在动态平衡。然后检查蛋白质和配体之间的疏水相互作用强度对吸附现象的影响。强疏水相互作用，代表流动相中存在高浓度溶致盐，可以加速吸附，但导致蛋白质展开更显着。相反，弱疏水相互作用，代表不存在溶致盐或存在离液剂，可以保留天然蛋白质构象，但不会导致稳定的吸附。在洗脱过程中，由于同时发生疏水吸附和相反方向的静电排斥，蛋白质发生去折叠。当蛋白质解吸时，由于静电相互作用的长程性质，仍然可以观察到未折叠蛋白质和天然蛋白质之间的构象转变。该模拟为整个HCIC过程中蛋白质构象转变提供了分子视角，有利于高性能HCIC配体的合理设计和参数优化。
Hydrophobic charge induction chromatography (HCIC) is an adsorption chromatography combining hydrophobic interaction in adsorption with electrostatic repulsion in elution. The method has been successfully applied in the separation and purification of antibodies and other proteins. However, little is understood about protein conformational transition and the dynamic process within adsorbent pores. In the present study, a pore model is established to represent the realistic porous adsorbent composed of matrix and immobilized HCIC ligands. Protein adsorption, desorption, and conformational transition in the HCIC pore and its implications to the separation performance are shown by a molecular dynamics simulation of a 46-bead beta-barrel coarse-grained model protein in the adsorbent pore. Repeated adjustment of both protein position and orientation is observed before reaching a stable adsorption. Once the protein is adsorbed, there is a dynamic equilibrium between unfolding and refolding. The effect of hydrophobic interaction strength between protein and ligands on adsorption phenomena is then examined. Strong hydrophobic interaction, representing the presence of high-concentration lyotropic salt in mobile phase, can speed up the adsorption but cause protein unfolding more significantly. On the contrary, weak hydrophobic interaction, representing the absence of a lyotropic salt or the presence of a chaotropic agent, can reserve native protein conformation but does not lead to stable adsorption. In the elution, protein unfolding occurs due to simultaneous hydrophobic adsorption and electrostatic repulsion in the opposite directions. When the protein has been desorbed, the conformational transition between unfolded and native protein is still observed due to the long-range nature of electrostatic interaction. The simulation has provided molecular insight into protein conformational transition in the whole HCIC process, and it would be beneficial to the rational design of ligands and parameter optimizations for high-performance HCIC.