Liu Changdeng, Vailhe Christophe, Samuel Newton, Min Qiang
Applied Science and Technology, Ethicon Inc., Route 22 West, Somerville, NJ 08876-0151, USA.
Int J Pharm. 2009 Jun 5;374(1-2):1-4. doi: 10.1016/j.ijpharm.2009.03.030. Epub 2009 Apr 5.
As the utility of proteins in medical diagnosis and therapy becomes more fully realized, interest in characterizing proteins' stability continues to increase. This paper reports the merits of rheology as an approach to characterizing the stability of a model protein, immunoglobulin (IgG). A controlled-strain rotational rheometer equipped with parallel plates geometry was used to measure changes in the viscosity of an IgG buffer solution during a programmed temperature ramp. The results demonstrated that protein stability characterization is reproducible using the melting temperature (or unfolding temperature) of IgG (T(m)=73.6+/-0.4 degrees C). We have also identified an irreversible minor transition occurring at a temperature of 40-60 degrees C, which we believe to be the partial unfolding of some protein structures. Finally, we have determined that adding sugar, an established protein stabilizer, to the IgG buffer solution significantly increases the protein's melting temperature. Our results show the power and simplicity of rheology as analytical tool for characterizing protein stability through the measurement of viscosity changes during thermal denaturation.
随着蛋白质在医学诊断和治疗中的效用得到更充分的认识，对表征蛋白质稳定性的兴趣持续增长。本文报道了流变学作为一种表征模型蛋白免疫球蛋白（IgG）稳定性方法的优点。使用配备平行板几何形状的控制应变旋转流变仪来测量在程序升温过程中IgG缓冲溶液粘度的变化。结果表明，使用IgG的解链温度（或展开温度）（T(m)=73.6±0.4℃）来表征蛋白质稳定性具有可重复性。我们还确定了在40-60℃温度下发生的不可逆的微小转变，我们认为这是一些蛋白质结构的部分展开。最后，我们确定向IgG缓冲溶液中添加糖类（一种公认的蛋白质稳定剂）会显著提高蛋白质的解链温度。我们的结果表明，流变学作为一种通过测量热变性过程中的粘度变化来表征蛋白质稳定性的分析工具，具有强大且简便的特点。
