The temperature-dependent secondary structure of two monoclonal IgG antibodies, anti-IGF1R and anti-TSLP, were examined by transmission mode Fourier Transform Infrared (FTIR) spectroscopy. Anti-IGF1R and anti-TSLP are IgG monoclonal antibodies (mAbs) directed against human Insulin-like Growth Factor 1 Receptor for anti-tumor activity and Thymic Stromal Lymphopoietin cytokine for anti-asthma activity, respectively. Differential scanning calorimetry (DSC) clearly indicates both antibodies in their base formulations have a lower temperature protein conformational change near 70 °C (T_m1) and a higher temperature protein conformational change near 85 °C (T_m2). Thermal scanning dynamic light scatting (TS-DLS) indicates a significant particle size increase for both antibodies near T_m2 suggesting a high level of protein aggregation. The nature of these protein conformational changes associated with increasing the formulation temperature and decreasing sucrose concentration were identified by transmission mode FTIR and second derivative FTIR spectroscopy of temperature controlled aqueous solutions of both monoclonal antibodies. The transition from intra-molecular β sheets to inter-molecular β sheets was clearly captured for both monoclonal antibodies using FTIR spectroscopy. Finally, FTIR Spectroscopy was able to show the impact of a common excipient such as sucrose on the stability of each monoclonal antibody, further demonstrating the usefulness of FTIR spectroscopy for studying protein aggregation and formulation effects.

中文翻译：

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FTIR光谱检测到两个单克隆抗体在高温Tm以上的分子间β-Sheet形成。

通过传输模式傅立叶变换红外（FTIR）光谱检查了两种单克隆IgG抗体（抗IGF1R和抗TSLP）的温度依赖性二级结构。抗IGF1R和抗TSLP分别是针对人类胰岛素样生长因子1受体的抗肿瘤活性和胸腺基质淋巴细胞生成素细胞因子的抗哮喘活性的IgG单克隆抗体（mAb）。差示扫描量热法（DSC）清楚地表明，两种抗体在其基本制剂中均在70°C（T _m1）附近具有较低温度的蛋白质构象变化，在85°C（T _m2）附近具有较高的温度蛋白构象变化。热扫描动态光散射（TS-DLS）表明两种抗体的显着粒径增加都接近T_m2表示高水平的蛋白质聚集。这些蛋白构象变化的性质与制剂温度升高和蔗糖浓度降低有关，这是通过两种单克隆抗体的温度控制水溶液的透射模式FTIR和二阶FTIR光谱学确定的。使用FTIR光谱法清楚地捕获了两种单克隆抗体从分子内β片层到分子间β片层的转变。最后，FTIR光谱能够显示出常见的赋形剂（如蔗糖）对每种单克隆抗体的稳定性的影响，进一步证明了FTIR光谱在研究蛋白质聚集和制剂作用方面的实用性。