Coleman Softlabs, Inc., Atherton, CA 94027, USA.
Protein J. 2011 Aug;30(6):395-403. doi: 10.1007/s10930-011-9344-y.
The purpose of this research is to study the thermal unfolding of high concentration bovine Immunoglobulin G (IgG) under 26 different experimental conditions by Fourier Transform Infrared spectroscopy with improved purge conditions and software calculations. When bovine IgG (25-200 mg/mL) was thermally denatured between pH 4.0 and 8.0, it was observed that at 25 mg/mL concentration, the protein exhibited maximum thermal stability at pH 6.0 and 7.0 as evident from the apparent T(m) values. Increasing the concentration from 25 to 100 mg/mL at those pH values increased the thermal resistance of the protein by 2-3 °C. But, at 200 mg/mL, IgG showed a small decrease in its transition temperature. Presence of 100 mM Trehalose enhanced the T(m) values at all conditions and possibly prevented the complete loss of IgG as insoluble aggregates at higher temperatures. Second derivative plots were constructed to explain the conformational changes of IgG during thermal unfolding.
本研究的目的是通过改进吹扫条件和软件计算，利用傅里叶变换红外光谱法研究 26 种不同实验条件下高浓度牛免疫球蛋白 G（IgG）的热变性。当牛 IgG（25-200mg/mL）在 pH 值为 4.0 至 8.0 之间热变性时，观察到在 25mg/mL 浓度下，该蛋白质在 pH 值为 6.0 和 7.0 时表现出最大的热稳定性，这从明显的 T(m)值可以看出。在这些 pH 值下，将浓度从 25mg/mL 增加到 100mg/mL 可使蛋白质的热稳定性提高 2-3°C。但是，在 200mg/mL 时，IgG 的转变温度略有下降。100mM海藻糖的存在提高了所有条件下的 T(m)值，并可能防止 IgG 在较高温度下完全失稳形成不溶性聚集体。绘制二阶导数谱以解释 IgG 在热变性过程中的构象变化。
