Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico.
Immunol Lett. 2012 Apr 30;143(2):152-60. doi: 10.1016/j.imlet.2012.01.010. Epub 2012 Jan 28.
The single-chain antibody fragment (scFv) 6009F, obtained by directed evolution, neutralizes the effects of the Cn2 toxin, which is the major toxic component of Centruroides noxius scorpion venom. In this work we compared the neutralization capacity and the thermodynamic stability of scFv 6009F with those of two other derived formats: Fab 6009F and diabody 6009F. Additionally, the affinity constants to Cn2 toxin of the three recombinant antibody fragments were determined by means of BIAcore. We found a correlation between the thermodynamic stability of these antibody fragments with their neutralization capacity. The order of thermodynamic stability determined was Fab≫scFv>diabody. The Fab and scFv were capable of neutralizing the toxic effects of Cn2 and whole venom but the diabody was unable to fully neutralize intoxication. In silico analysis of the diabody format indicates that the reduction of stability and neutralization capacity could be explained by a less cooperative interface between the heavy and the light variable domains.
单链抗体片段 (scFv) 6009F 通过定向进化获得，可中和 Cn2 毒素的作用，Cn2 毒素是 Centruroides noxius 蝎毒液的主要毒性成分。在这项工作中，我们比较了 scFv 6009F 与另外两种衍生形式（Fab 6009F 和二价体 6009F）的中和能力和热力学稳定性。此外，还通过 BIAcore 测定了这三种重组抗体片段与 Cn2 毒素的亲和常数。我们发现这些抗体片段的热力学稳定性与其中和能力之间存在相关性。根据热力学稳定性确定的顺序为 Fab≫scFv>二价体。Fab 和 scFv 能够中和 Cn2 毒素和全毒液的毒性作用，但二价体不能完全中和中毒。二价体形式的计算分析表明，稳定性和中和能力的降低可以用重链和轻链可变区之间的界面协同性降低来解释。
