Transition towards antigen-binding promiscuity of a monospecific antibody
Transition towards antigen-binding promiscuity of a monospecific antibody
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DOI：
10.1016/j.molimm.2006.10.002
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发表时间：
2007-03-01
影响因子：
3.6
通讯作者：
Vassilev, Tchavdar L.
中科院分区：
文献类型：
--
作者：
Dimitrov, Jordan D.;Lacroix-Desmazes, Sebastien;Vassilev, Tchavdar L.
多特异性定义为给定抗体分子结合大量结构不同抗原的能力。所有健康个体中循环 IgG 的一小部分仅在短暂暴露于某些蛋白质不稳定因素后才获得混杂的抗原结合活性。这种现象的分子机制尚不清楚。暴露于蛋白质去稳定剂是免疫球蛋白分离和纯化过程中的常见步骤。我们使用基于表面等离子共振的技术进行了动力学和热力学分析，以表征单个小鼠单克隆抗体在诱导混杂抗原结合活性之前和之后与其同源抗原的相互作用。获得的结果表明，暴露于温和变性条件诱导的抗原结合活性增强是由于抗原结合位点结构灵活性的增加所致。对抗体/抗原相互作用的进一步 pH 和离子强度依赖性分析表明，向混杂抗原结合的转变伴随着复合物形成中涉及的非共价力类型的变化。此外，从这项研究中可以明显看出，抗体分子可以使用两种不同的热力学途径来结合相同的抗原，同时保留相同的结合亲和力值。获得的结果可能有助于理解天然抗体多特异性背后的分子机制。 (c) 2006 Elsevier Ltd. 保留所有权利。
Polyspecificity is defined as the ability of a given antibody molecule to bind a large panel of structurally diverse antigens. A fraction of circulating IgG in all healthy individuals acquires promiscuous antigen-binding activity only after a transient exposure to certain protein destabilizing factors. The molecular mechanisms of this phenomenon are not well understood. Exposures to protein destabilizing agents are common steps in immunoglobulin isolation and purification processes. We performed kinetic and thermodynamic analyses using surface plasmon resonance-based technique in order to characterize the interactions of a single mouse monoclonal antibody to its cognate antigen before and after induction of promiscuous antigen-binding activity. The obtained results, suggest that enhanced antigen binding activity induced by exposure to mild denaturing condition resulted from an increase in the structural flexibility of the antigen-binding site. Further pH and ionic strength-dependence analyses of the antibody/antigen interactions demonstrated that the transition to promiscuous antigen-binding was accompanied by a change in the type of non-covalent forces involved in the complex formation. Moreover, from this study, it is evident that an antibody molecule could use two distinct thermodynamic pathways for binding to the same antigen while retaining the same value of the binding affinity. The obtained results may contribute to the understanding of the molecular mechanisms that lay behind natural antibody polyspecificity. (c) 2006 Elsevier Ltd. All rights reserved.