Infrared spectroscopic studies of ionic and neutral biomolecules and their solvated complexes

本文的研究重点是中性和离子型分子和配合物的结构解析，特别是那些参与弱分子内键的分子和配合物。在自然状态下，蛋白质和其他生物分子是多重质子化的。它们也可以与金属阳离子结合，这通常是生物活性所必需的。拟议的研究将通过研究这些物种在低温下从稀有气体基质中分离出来的红外光谱，从而深入了解存在于生物学相关分子中的显着的弱分子内相互作用，在低温下它们可以被无限期地存储和研究。与分子另一部分的相互作用程度（分子内键）可以通过红外吸收位置的移动来研究。例如，当甘氨酸与钠离子结合时，其中一个异构体预计会在羰基氧和氨基氢之间表现出很强的分子内氢键。从正常的N-H拉伸来看，N-H拉伸红移了大约800个波数。为了弥合气相分子和自然溶剂化状态下分子的内在性质之间的差距，将研究顺序溶剂化（与1,2或更多溶剂分子如水）生物学上感兴趣的离子和中性物质的影响。通过提出的实验，我们将能够评估在溶剂化的每个阶段发生的结构变化。这项研究有望在确定生命组成部分的结构以及溶剂对结构的影响方面发挥重要作用。这将使我们对生物分子的作用和溶剂在生物活性中的作用有更详细、更基本的了解。此外，这项研究将提供生物离子和中性的光谱特征，最终有助于使用红外光谱进行诊断。

The proposed research is focused on the structure elucidation of both neutral and ionic molecules and complexes, especially those which can participate in weak intramolecular bonding.  In their natural state, proteins and other biological molecules are multiply protonated. They can also be bound to metal cations and this is often required for biological activity.  The proposed research will provide insight into the salient weak intramolecular interactions which are present in biologically relevant molecules by studying the infrared spectra of these species isolated in rare-gas matrices at cryogenic temperatures where they can be stored and studied indefinately.  The degree of interaction with another portion of the molecule (intramolecular bonding) can be studied by the shifts in  position of the infrared absorption.  For example, when glycine is bound to a sodium cation, one of the isomers is expected to exhibit strong intramolecular hydrogen bonding between a carbonyl oxygen and an amino hydrogen.  The N-H stretch is seen to red-shift by some 800 wavenumbers from that of a normal N-H stretch.   The effect of sequentially solvating (with 1, 2 or more solvent molecules such as water) biologically interesting ions and neutrals will be studied in order to bridge the gap between the intrinsic properties of the gas-phase molecule and those of the molecule in its natural, solvated state.  With the proposed experiments we will be able to assess the structural changes which occur at each stage solvation. This research is expected to play an important role in determining the structure, and the effect of solvent on the structure, of life's building blocks.  This will lead to a more detailed, fundamental understanding of the role of the biomolecule and the role of solvent in biological activity.  Furthermore, this research will provide spectral signatures for biological ions and neutrals which can eventually aid in the use of infrared spectroscopy for diagnostic purposes.