Bio-Molecular Thermodynamics of Protein Precipitation in Aqueous Solutions

实验和理论生物处理研究是 致力于发展一种分子热力学 用于从以下物质的混合物中分离靶蛋白的模型 蛋白质在水溶液中。 实现蛋白质分离 通过由盐、非离子聚合物或两者引起的沉淀。 所得系统由两个液相组成， 一种是富含靶蛋白的。 一 分子热动力学模型概述了描述 蛋白质沉淀相平衡 该模型是由 从对分子间力的理解 沉淀溶液;它使用平均球- 将参考系统定义为以下各项的混合近似 带电的硬球 这个参考系的扰动 由色散力、偶极-偶极力和 也许是特定的联合力量 渗透压 将从模型计算的压力与 从膜渗透压测定法和渗透秒获得的数据 小角度激光法测维里系数 散射 实验相平衡（沉淀） 测量将提供数据， 热力学模型可以比较。 蛋白质聚集体大小 来自光散射的分布数据将用于 当发生显著聚集时，增强理论。 的 本研究的目标是建立一个工程导向的 蛋白质沉淀合理设计的相关性 流程. 这项研究的长期好处是， 很可能会提供有用的知识， 了解蛋白质结晶的生物过程。

Experimental and theoretical bio-processing studies are directed toward the development of a molecular-thermodyamic model for separationg a target protein from a mixture of proteins in aqueuous solution. Protein separation is achieved by precipitation induced by salts, nonionic polymers, or both. The resulting system consists of two liquid phases in equilbrium, with one enriched in the target protein. A molecular-thermosynamic model is outlined for describing protein-precipitation phase equilibria. This model is derived from an understanding of the intermolecular forces in the precipitating solutions; it uses the mean-spherical- approximation to define the reference system as a mixture of charged hard spheres. Pertubations to this reference system result from the dispersion forces, dipole-dipole forces and perhaps, specific association forces. Osmotic pressures calculated from the model will be compared to osmotic-pressure data obtained from membrane osmometry and to osmotic second virial coefficients measured by low-angle laser-light scattering. Experimental phase-equilibrium (precipitation) measurements will provide data against which the molecular- thermodynamic model can be compared. Protein aggregate size distribution data from light scattering will be used to augment the theory when significant aggregation occurs. The goal of this reech is to establish an engineering-oriented correlation for the rational design of protein-precipitation processes. The long-range benefit of this research is that it is likely to provide useful knowledge for a better understanding of protein crystallization bioprocesses.