Université d'Evry val d'Essonne, LAMBE UMR8587 Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Blvd F. Mitterrand, Bat Maupertuis, 91025 Evry, France.
Phys Chem Chem Phys. 2010 Apr 14;12(14):3336-59. doi: 10.1039/b924048a. Epub 2010 Mar 10.
Theoretical spectroscopy is mandatory for a precise understanding and assignment of experimental spectra recorded at finite temperature. We review here room temperature DFT-based molecular dynamics simulations for the purpose of interpreting finite temperature infrared spectra of peptides of increasing size and complexity, in terms of temperature-dependent conformational dynamics and flexibility, and vibrational anharmonicities (potential energy surface anharmonicities, vibrational mode couplings and dipole anharmonicities). We take examples from our research projects in order to illustrate the main key-points and strengths of dynamical spectra modeling in that context. The calculations are presented in relation to room temperature gas phase IR-MPD experiments and room temperature liquid phase IR absorption experiments. These illustrations of floppy polypeptides have been chosen in order to convey the following ideas: temperature-dependent spectra modeling is pivotal for a precise understanding of gas phase spectra recorded at room temperature, including conformational dynamics and vibrational anharmonicities; harmonic spectroscopy (as commonly performed in the literature) can be misleading and even erroneous for a proper interpretation of spectra recorded at finite temperature; taking into account vibrational anharmonicities is pivotal for a proper interplay between theory and experiments; amide I-III bands are not necessarily the most relevant fingerprints for unraveling the local structures of peptides and more complex systems; liquid phase simulations have unraveled relationships between the zwitterionic properties of the peptide bonds and infrared signatures. The review presents a state-of-the-art account of the domain and offers perspectives and new developments for future still more challenging applications.
理论光谱对于精确理解和分配在有限温度下记录的实验光谱是必不可少的。在这里，我们回顾了基于密度泛函理论（DFT）的室温分子动力学模拟，目的是根据温度相关的构象动力学和灵活性以及振动非谐性（势能面非谐性、振动模式耦合和电偶极非谐性），解释越来越大且复杂的肽的有限温度红外光谱。我们从我们的研究项目中举例说明了在这种情况下动态光谱建模的主要要点和优势。这些计算与室温气相 IR-MPD 实验和室温液相 IR 吸收实验有关。选择这些柔性多肽的例子是为了传达以下思想：温度相关的光谱建模对于精确理解在室温下记录的气相光谱至关重要，包括构象动力学和振动非谐性；对于在有限温度下记录的光谱的正确解释，谐波光谱（如文献中常见的那样）可能会产生误导，甚至是错误的；考虑振动非谐性对于理论与实验之间的恰当相互作用至关重要；酰胺 I-III 带不一定是揭示肽和更复杂体系局部结构的最相关指纹；液相模拟揭示了肽键的两性离子性质与红外特征之间的关系。本综述介绍了该领域的最新进展，并为未来更具挑战性的应用提供了展望和新的发展方向。
