Proteins at interfaces play important roles in cell biology, immunology, bioengineering, and biomimetic material design. Many biological processes are based on interfacial protein action, ranging from cellular communication to immune responses and the protein-driven mineralization of bone. Despite the importance of interfacial proteins, comparatively little is known about their structure. The standard methods for studying crystalline or solution-phase proteins (X-ray diffraction and NMR spectroscopy) are not well-suited for studying proteins at interfaces, and for these proteins we still lack a corresponding technique that can provide the same level of structural resolution. This is not surprising in view of the challenges involved in probing the structure of proteins within monomolecular films assembled at a very thin interface in situ. Vibrational sum-frequency generation (SFG) spectroscopy has the potential to overcome this challenge and investigate the structure and dynamics of proteins at interfaces at the molecular level with subpicosecond time resolution. While SFG studies were initially limited to simple model peptides, the past decade has seen a dramatic advancement of experimental techniques and data analysis methods that has made it possible to also study interfacial proteins and their folding, binding, orientation, hydration, and dynamics. In this review, we first explain the principles of SFG spectroscopy and the experimental and theoretical methods to measure and analyze protein SFG spectra. Then we give an extensive overview of the interfacial proteins studied to date with SFG. We highlight representative examples to demonstrate recent advances in probing the structure of proteins at the interfaces of liquids, membranes, minerals, and synthetic materials.

中文翻译：

---

振动和频产生光谱的界面肽和蛋白质的结构和动力学。

界面蛋白在细胞生物学，免疫学，生物工程和仿生材料设计中起着重要作用。许多生物学过程都基于界面蛋白的作用，范围从细胞通讯到免疫反应以及蛋白质驱动的骨骼矿化。尽管界面蛋白很重要，但对其结构的了解相对较少。研究结晶或溶液相蛋白质的标准方法（X射线衍射和NMR光谱法）不适合研究界面蛋白质，对于这些蛋白质，我们仍然缺乏可以提供相同水平结构分辨率的相应技术。 。考虑到探测在原位非常薄的界面处组装的单分子膜中的蛋白质结构所涉及的挑战，这不足为奇。振动和频产生（SFG）光谱技术有可能克服这一挑战，并以亚皮秒的时间分辨率在分子水平的界面上研究蛋白质的结构和动力学。尽管SFG研究最初仅限于简单的模型肽，但在过去的十年中，实验技术和数据分析方法取得了显着进步，这使得研究界面蛋白及其折叠，结合，定向，水合和动力学成为可能。在这篇综述中，我们首先解释了SFG光谱的原理以及测量和分析蛋白质SFG光谱的实验和理论方法。然后，我们对迄今为止使用SFG研究的界面蛋白进行了广泛的概述。