Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
J Phys Chem B. 2013 Dec 12;117(49):15527-35. doi: 10.1021/jp405852r. Epub 2013 Aug 23.
We explore the structure and orientation of N-terminal (23 amino acids) of HIV gp41 envelop protein at the interface of a phospholipid monolayer. Using surface specific sum frequency generation, we probe the response of the Amide I vibrational states of the protein, and compare the experimental results to the modeled response of several secondary structures that have previously been reported in literature. To obtain the modeled response, we derive the line-shape expressions under cumulant expansion within the Brownian oscillator model, and express the intensities of the theoretical response according to the components of the Raman tensors and the infrared transition dipole moments of the relevant Amide I modes, under different orientation angles. This approach enables us to identify one plausible secondary structure among those considered, and allows us to determine the orientation angle, under which the protein inserts into the monolayer. We discuss the relevance of our findings toward understanding the functionality of this polypeptide at the membrane interface.
我们探索了 HIV gp41 包膜蛋白 N 端（23 个氨基酸）在磷脂单层界面处的结构和取向。利用表面特定的和频产生技术，我们探测了蛋白质酰胺 I 振动态的响应，并将实验结果与文献中报道的几种二级结构的模型响应进行了比较。为了获得模型响应，我们在布朗振子模型的累积展开下推导出了线宽表达式，并根据相关酰胺 I 模式的拉曼张量分量和红外跃迁偶极矩，按照不同的取向角来表达理论响应的强度。这种方法使我们能够在考虑的结构中确定一种合理的二级结构，并确定该蛋白质插入单层的取向角。我们讨论了我们的发现对于理解该多肽在膜界面处的功能的相关性。
