VIBRATIONAL OPTICAL ACTIVITY IN PEPTIDE MOLECULES

振动旋光性，包括振动圆二色性 (VCD)和拉曼光学活性（罗阿），将得到进一步发展， 应用于肽分子的立体化学方面。 这项研究将 利用最近建造的二极管阵列罗阿摄谱仪， 高分辨率傅里叶变换红外（FTIR）光谱仪， VCD测量、色散、光栅VCD仪器和色散 用于测量光谱的拉曼光谱仪。 为了提高效率，罗阿 光谱仪将配置为独立仪器， 激光器和光学表面。 氨基酸、肽、多肽、模型 化合物和衍生物将作为溶剂，pH值（pD）， 过渡金属络合和同位素取代。 罗阿居留权工作将 关注VCD调查和调查代表的富有成果的领域 分子分类 VCD工作的重点将是确定 肽分子中VCD对二级结构的敏感性， 亚基偶联和分子内氢键结合以及旋转异构体 关于C α-CBeta键的侧链分布。 光谱 解释将涉及振动正常坐标分析的 丙氨酸以外的更简单的氨基酸，模型肽和相关分子 片段 VCD和罗阿强度计算的新方法将在 并与实验进行比较。 最近制定的非绝热， 振动诱导电子的非Born-Oppenheimer表达式 将电流密度应用于氨基中的分子内氢键 酸和肽来测试可疑的磁环电流， 在这些分子中产生大的单信号VCD强度。 长 本研究的范围目标是描述构象和 具有特异性的生物活性肽的自缔合特征 生物学、神经学和药理学相关性，例如简单的 激素肽、肌肽、黑素抑制素和脑啡肽 神经肽 更一般的目标是进一步发展VCD和罗阿， 构象、振动和电子的立体化学探针 电荷和电流分布的所有类别的手性生物 分子。

Vibrational optical activity, comprised of vibrational circular dichroism (VCD) and Raman optical activity (ROA), will be further developed and applied to stereochemical aspects of peptide molecules. The research will make use of a recently constructed diode-array ROA spectrograph, a high-resolution Fourier transform infrared (FTIR) spectrometer equipped for VCD measurement, a dispersive, grating VCD instrument and a dispersive Raman spectrometer for survey spectra. For improved efficiency the ROA spectrograph will be configured as a stand-alone instrument with its own laser and optical surface. The amino acids, peptides, polypeptides, model compounds and derivatives will be studied as functions of solvent, pH(pD), transition metal complexation and isotopic substitution. The ROA work will follow fruitful areas of VCD investigation and survey representative molecular classes. The focus of VCD work will be to determine the extent of sensitivity of VCD in peptide molecules to secondary structure via subunit coupling and intramolecular hydrogen bonding an to rotameric side-chain distributions about the CAlpha-CBeta bond. Spectral interpretation will involve vibrational normal coordinate analysis for the simpler amino acids beyond alanine, model peptides and relevant molecular fragments. New methods of VCD and ROA intensity calculations will be carried out to compare with experiment. Recently formulated a-diabatic, non-Born-Oppenheimer expressions for vibrationally induced electronic current density will be applied to intramolecular hydrogen bonding in amino acids and peptides to test for suspected magnetic ring currents that produce large, monosignate VCD intensity in these molecules. The long range goal of this research is to describe the conformational and self-associative features of bioactive peptides that have specific biological, neurological and pharmacological relevance, such as the simple hormonal peptides, carnosine and melanostatin and the enkephalin neuropeptides. A more general goal is to further develop VCD and ROA as stereochemical probes of conformation, vibrational motion, and electronic charge and current distributions for all classes of chiral biological molecules.