Tong Hong-Fei, Cavallotti Carlo, Yao Shan-Jing, Lin Dong-Qiang
Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Via Mancinelli 7, Milan 20131, Italy.
J Chromatogr A. 2017 Aug 25;1512:34-42. doi: 10.1016/j.chroma.2017.06.071. Epub 2017 Jun 30.
Hydrophobic charge-induction chromatography (HCIC) with 4-mercaptoethyl-pyridine (MEP) as the functional ligand has been developed as a new technology for antibody purification. In the present work, molecular simulation methods were developed to investigate the interactions between the Fc fragment of IgG and a MEP ligand net. The MM/PBSA method was used to evaluate the binding energy for the MEP ligand net at different densities. It was found that ligand density had significant influence on the binding of Fc. Potential binding conformations were further analyzed by molecular dynamics simulation. It was found that the interaction between Fc and MEP ligand net is driven by self-adaptive conformation adjustment and multiple-site binding. Hydrophobic forces dominate the binding interaction, which appeared as the results of synergistic actions of binding sites located on CH2, CH3, and the consensus binding site (CBS) of the Fc fragment. At acidic pH, the electrostatic repulsion between the basic residues and the protonated pyridine ring group on MEP ligands is the main driving force for the detachment of the Fc fragment from the MEP net.
以4-巯基乙基吡啶（MEP）为功能配体的疏水电荷诱导色谱（HCIC）已被开发为一种用于抗体纯化的新技术。在本研究中，开发了分子模拟方法来研究IgG的Fc片段与MEP配体网络之间的相互作用。采用MM/PBSA方法评估不同密度下MEP配体网络的结合能。发现配体密度对Fc的结合有显著影响。通过分子动力学模拟进一步分析了潜在的结合构象。发现Fc与MEP配体网络之间的相互作用是由自适应构象调整和多位点结合驱动的。疏水作用力主导结合相互作用，这是位于Fc片段的CH2、CH3和共有结合位点（CBS）上的结合位点协同作用的结果。在酸性pH值下，碱性残基与MEP配体上质子化吡啶环基团之间的静电排斥是Fc片段从MEP网络上解离的主要驱动力。
