Structure-based affinity maturation of a chimeric anti-ricin antibody C4C13
Structure-based affinity maturation of a chimeric anti-ricin antibody C4C13
复制标题
嵌合抗蓖麻毒素抗体 C4C13 基于结构的亲和力成熟
DOI：
10.1080/07391102.2013.771380
复制
发表时间：
2014-03-04
影响因子：
4.4
通讯作者：
Feng, Jiannan
中科院分区：
文献类型：
--
作者：
Luo, Longlong;Luo, Qun;Feng, Jiannan
蓖麻毒素是一种高度致命的毒素。本实验室制备了抗蓖麻毒素嵌合单克隆抗体C4 C13，但其结合亲和力远低于亲本抗体4C 13。本研究基于计算机引导的同源模建和构象优化方法，构建并优化了C4 C13可变区Fv的三维结构。利用分子对接和动力学模拟方法，获得了蓖麻毒素与C4 C13 Fv的三维复合结构。从分子的取向性、表面静电分布、残基的物理化学性质和分子间氢键等方面对键合模式和关键残基进行了预测。根据C4 C13 Fv片段与蓖麻毒素互补结合表面、静电吸引周边和货车范德华相互作用界面，M1（NH 102 F，WH 103 Y）; M2（WH 103 Y）和M3（RL 90 G）），其中M1和M2具有比C4 C13更高的抗原结合活性，而M3则较弱。通过ELISA进行的相对亲和力测定显示，M1和M2突变的亲和力（9.6和18.3 nmol/L）高于C4 C13（130 nmol/L），M3的亲和力（234.5 nmol/L）低于C4 C13。结果表明，抗原（蓖麻毒素）和抗体（C4 C13）的模拟复合物结构是合理的。本研究通过定点突变的方法获得了亲和性成熟的抗体，为下一步抗蓖麻毒素抗体的设计和制备奠定了基础。
Ricin is a highly lethal toxin. Anti-ricin chimeric monoclonal antibody (mAb) C4C13 was prepared in our lab; however, its binding affinity was much weaker than that of the parent antibody 4C13. In this study, based on the computer-guided homology modeling and conformational optimization methods, the 3-D structure of C4C13 variable regions Fv was constructed and optimized. Using molecular docking and dynamics simulation methods, the 3-D complex structure of ricin and C4C13 Fv was obtained. Considering the orientation property, surface electrostatic distribution, residues chemical andphysical character and intermolecular hydrogen bond, the binding mode and key residues were predicted. According to C4C13 Fv fragment and ricin complementary binding surface, electrostatic attraction periphery and van der Waals interaction interface, three mutants (i.e., M1 (NH102F, WH103Y); M2 (WH103Y) and M3 (RL90G)) were designed, in which M1 and M2 were predicted to possess higher antigen-binding activity than C4C13, while M3 was weaker. The relative affinity assays by ELISA showed that M1 and M2 mutations had higher affinity (9.6 and 18.3 nmol/L) than C4C13 (130 nmol/L) and M3 had weaker affinity (234.5 nmol/L) than C4C13. The results showed that the modeling complex structure of the antigen (ricin) and antibody (C4C13) is reasonable. Our work offered affinity maturated antibodies by site mutations, which were beneficial for valuable anti-ricin antibody design and preparation in future.