IR laser spectroscopy of molecular structures & dynamics of bio-mimetics, & dynamics of bio-mimetics, & spectroscopic studies of large-amplitude motions in molecules of astrochemical & atmospheric imp

分子结构的红外激光光谱

• 批准号: 170160-2008
• 负责人: Xu, LiHong
• 金额: $ 2.48万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=593548
• 关键词: IR; laser; spectroscopy; molecular; structures

One of the fascinating current questions in molecular and biological physical chemistry is the mechanism of protein folding. What are the energetics and the dynamics of the motions of these large biomolecules? To seek insights, we will undertake high-resolution spectroscopic study of biomimetics at UNB and the FIR beamline at the CLS synchrotron in Saskatoon. Biomimetics are medium-sized molecules which mimic the structures and internal motions of subunits of larger biomolecules, providing windows into the folding behaviour and torsional flexibility of the larger parents. We will study the weak torsional fundamentals at the CLS taking advantage of the bright synchrotron source, and we will probe bending and stretching vibrations of the heavy-atom molecular backbones in-house at UNB to exploit these modes as "doorway" states to couple to and give information about the torsion. Using complementary experimental and ab-initio approaches, we aim to explore (i) the number, shape and energy of different molecular conformations, (ii) barriers to folding, and (iii) tunneling pathways, features all directly related to the folding structures in peptide chains. Our second area of research deals with the complex interactions between vibrations and torsion in smaller molecules such as methanol. Here, we are analyzing the IR absorption bands in order to understand and model the energy structure and intermode coupling, and to provide information to a wide audience of atmospheric and space scientists. Recent observations of methanol in forest fires, the atmosphere and comets have generated a strong demand for database information. Astronomically, methanol is now identified as the worst interstellar "weed" with an abundance of strong lines throughout the entire spectrum that interfere with other molecules of interest. A collaboration with the NASA Jet Propulsion Lab on compilation of position and intensity data will fill an important gap in the next version of HITRAN, the international atmospheric database. To further advance the frontiers, we will initiate multi-state global modeling for much improved accuracy and capability for reliable simulation of methanol absorption bands over a wide range of atmospheric and astrochemical conditions.

蛋白质折叠机制是当前分子和生物物理化学领域的一个热点问题。这些大型生物分子的运动的能量学和动力学是什么？为了寻求见解，我们将在UNB和萨斯卡通的CLS同步加速器的FIR光束线进行仿生学的高分辨率光谱研究。仿生学是中等大小的分子，其模拟较大生物分子的亚基的结构和内部运动，为较大亲本的折叠行为和扭转柔性提供窗口。我们将利用明亮的同步加速器光源研究CLS的弱扭转基本原理，我们将探测UNB内部重原子分子骨架的弯曲和拉伸振动，以利用这些模式作为“门口”状态来耦合并提供有关扭转的信息。使用互补的实验和从头算方法，我们的目标是探索（i）不同分子构象的数量，形状和能量，（ii）折叠的障碍，和（iii）隧穿途径，所有这些特征都直接与肽链中的折叠结构相关。我们的第二个研究领域涉及较小分子（如甲醇）中振动和扭转之间的复杂相互作用。在这里，我们正在分析红外吸收带，以了解和建模的能量结构和模间耦合，并提供信息给广大观众的大气和空间科学家。最近对森林火灾、大气和彗星中甲醇的观察产生了对数据库信息的强烈需求。在天文学上，甲醇现在被认为是最糟糕的星际“杂草”，在整个光谱中有大量的强谱线干扰其他感兴趣的分子。与美国航天局喷气推进实验室合作汇编位置和强度数据，将填补国际大气数据库HITRAN下一版本的一个重要空白。为了进一步推进前沿，我们将启动多状态全球建模，以大大提高在广泛的大气和天体化学条件下可靠模拟甲醇吸收带的准确性和能力。