Department of Chemistry , University of Basel , Klingelbergstrasse 80 , CH-4056 Basel , Switzerland.
J Phys Chem B. 2019 Apr 18;123(15):3282-3290. doi: 10.1021/acs.jpcb.8b11430. Epub 2019 Apr 3.
Azido-derivatized amino acids are potentially useful, positionally resolved spectroscopic probes for studying the structural dynamics of proteins and macromolecules in solution. To this end, a computational model for the vibrational modes of N based on accurate electronic structure calculations and a reproducing kernel Hilbert space representation of the potential energy surface for the internal degrees of freedom is developed. Fully dimensional quantum bound state calculations yield the antisymmetric stretch vibration at 1974 cm compared with 1986 cm from experiment. This mode shifts by 64 cm (from the frequency distribution) and 74 cm (from the IR line shape) to the blue, respectively, compared with 61 cm from experiment for N in water. The decay time of the frequency fluctuation correlation function is 1.1 ps, which is in good agreement with experiment (1.2-1.3 ps) and the full width at half maximum of the asymmetric stretch in solution is 18.5 cm compared with 25.2 cm from experiment. A computationally more efficient analysis based on instantaneous normal modes is shown to provide comparable, albeit somewhat less quantitative results compared to solving the three-dimensional Schrödinger equation for the fundamental vibrations.
叠氮基衍生的氨基酸是研究溶液中蛋白质和生物大分子结构动力学的潜在有用的、位置分辨的光谱探针。为此，开发了一种基于精确电子结构计算和内部自由度势能面的再生核希尔伯特空间表示的 N 原子振动模式的计算模型。全维量子束缚态计算得到的反对称伸缩振动频率为 1974cm，而实验值为 1986cm。与实验相比，该模式分别向蓝移 64cm（从频率分布）和 74cm（从红外线形状），而 N 在水中的蓝移为 61cm。频率波动相关函数的衰减时间为 1.1ps，与实验值（1.2-1.3ps）吻合较好，溶液中不对称伸缩的半峰全宽为 18.5cm，而实验值为 25.2cm。基于瞬时法向模式的计算分析表明，与求解基本振动的三维薛定谔方程相比，它可以提供可比的、尽管稍欠定量的结果。
