Chemical Sciences Division, Chemical Informatics Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899; Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850.
Chemical Sciences Division, Chemical Informatics Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
J Pharm Sci. 2019 May;108(5):1663-1674. doi: 10.1016/j.xphs.2018.12.013. Epub 2018 Dec 26.
Employing 2 different coarse-grained models, we evaluated the effect of intramolecular domain-domain distances and hinge flexibility on the general solution structure of monoclonal antibodies (mAbs), within the context of protein-protein steric repulsion. These models explicitly account for the hinge region, and represent antibodies at either domain or subdomain levels (i.e., 4-bead and 7-bead representations, respectively). Additionally, different levels of mAb flexibility are also considered. When evaluating mAbs as rigid structures, analysis of small-angle scattering profiles showed that changes in the relative internal distances between Fc and Fab domains significantly alter the local arrangement of neighboring molecules, as well as the molecular packing of the concentrated mAb solutions. Likewise, enabling hinge flexibility in either of the mAb models led to qualitatively similar results, where flexibility increases the spatial molecular arrangement at elevated concentrations. This occurs because fluctuations in mAb quaternary structure are modulated by the close proximity between molecules at elevated concentrations (>50 mg mL), yielding an increased molecular packing and osmotic compressibility. However, our results also showed that the mechanism behind this synergy between flexibility and packing strongly depends on both the level of structural detail and the number of degrees-of-freedom considered in the coarse-grained model.
我们使用两种不同的粗粒化模型，在蛋白质-蛋白质空间位阻的背景下，评估了分子内结构域-结构域距离和铰链柔性对单克隆抗体 (mAb) 总体溶液结构的影响。这些模型明确考虑了铰链区域，并分别在结构域或亚结构域水平上代表抗体 (即 4 珠和 7 珠表示)。此外，还考虑了不同水平的 mAb 柔性。当将 mAb 评估为刚性结构时，小角度散射曲线的分析表明，Fc 和 Fab 结构域之间的相对内部距离的变化显著改变了相邻分子的局部排列以及浓缩 mAb 溶液的分子堆积。同样，在任一种 mAb 模型中使铰链柔性化都导致了定性相似的结果，其中柔性在高浓度下增加了空间分子排列。这是因为在高浓度 (>50mg/mL) 下，分子之间的近距离调节了 mAb 四级结构的波动，从而增加了分子堆积和渗透压。然而，我们的结果还表明，这种柔性和堆积之间协同作用的机制强烈依赖于粗粒化模型中所考虑的结构细节水平和自由度数量。
