Rowe Jacob B, Cancel Rachel A, Evangelous Tyler D, Flynn Rhiannon P, Pechenov Sergei, Subramony J Anand, Zhang Jifeng, Wang Ying
Department of Chemistry and Biochemistry, University of North Carolina at Wilmington, Wilmington, North Carolina.
MedImmune, Gaithersburg, Maryland.
Biophys J. 2017 Oct 17;113(8):1750-1756. doi: 10.1016/j.bpj.2017.08.048.
Crystallization of IgG antibodies has important applications in the fields of structural biology, biotechnology, and biopharmaceutics. However, a rational approach to crystallize antibodies is still lacking. In this work, we report a method to estimate the solubility of antibodies at various temperatures. We experimentally determined the full phase diagram of an IgG antibody. Using the full diagram, we examined the metastability gaps, i.e., the distance between the crystal solubility line and the liquid-liquid coexistence curve, of IgG antibodies. By comparing our results to the partial phase diagrams of other IgGs reported in literature, we found that IgG antibodies have similar metastability gaps. Thereby, we present an equation with two phenomenological parameters to predict the approximate location of the solubility line of IgG antibodies with respect to their liquid-liquid coexistence curves. We have previously shown that the coexistence curve of an antibody solution can be readily determined by the polyethylene glycol-induced liquid-liquid phase separation method. Combining the polyethylene glycol-induced liquid-liquid phase separation measurements and the phenomenological equation in this article, we provide a general and practical means to predict the thermodynamic conditions for crystallizing IgG antibodies in the solution environments of interest.
IgG抗体的结晶在结构生物学、生物技术和生物制药领域有着重要应用。然而，目前仍缺乏一种合理的抗体结晶方法。在这项工作中，我们报告了一种估算抗体在不同温度下溶解度的方法。我们通过实验确定了一种IgG抗体的完整相图。利用该完整相图，我们研究了IgG抗体的亚稳间隙，即晶体溶解度线与液-液共存曲线之间的距离。通过将我们的结果与文献中报道的其他IgG的部分相图进行比较，我们发现IgG抗体具有相似的亚稳间隙。因此，我们提出了一个包含两个唯象参数的方程，以预测IgG抗体溶解度线相对于其液-液共存曲线的大致位置。我们之前已经表明，抗体溶液的共存曲线可以通过聚乙二醇诱导的液-液相分离方法轻松确定。结合本文中的聚乙二醇诱导的液-液相分离测量和唯象方程，我们提供了一种通用且实用的方法，来预测在感兴趣的溶液环境中结晶IgG抗体的热力学条件。
