MRI: Acquisition of a Spectropolarimeter for Circular Dichroism and Magnetic Circular Dichroism Experiments

明德学院化学系将从主要研究仪器（MRI）项目获得一台分光偏振仪。它将与可变磁场磁铁耦合，以实现磁圆二色性（MCD）和圆二色性（CD）测量。由首席研究员（PI）进行的研究将利用变温度、变磁场磁圆二色性来确定一系列羧酸桥接Co（II）二聚体配合物和含有双核Co（II）的酶活性位点的磁偶联强度。这将提供一个更详细的图像的电子基态结构的这种活性位点motif普遍存在于自然界。MCD将被co-PI用于Ru（III）配合物与DNA类似物相互作用的探索性实验。另外两名明德大学生物化学教授将使用该仪器收集CD数据，用于蛋白质二级结构分析。圆二色光谱偏振仪将产生圆二色光谱数据，提供有关分子结构的信息，特别是生物分子的构象，如蛋白质、酶和核酸。在磁圆二色性中，手性是由平行于光传播方向的强磁场引起的，这种现象被称为法拉第效应。MCD强度随温度和场强的变化取决于金属的电子基态。因此，MCD是小配合物和蛋白质活性位点中与顺磁性金属离子相关的电子结构的敏感探针。该仪器将用于本科生的研究。这种培训将使学生在各种职业中，特别是在化学、生物和健康相关领域中，能够利用这种复杂的技术。

The Department of Chemistry at Middlebury College will acquire a spectropolarimeter with this award from the Major Research Instrumentation (MRI) program. It will be coupled to a variable field magnet to enable magnetic circular dichroism (MCD) as well as circular dichroism (CD) measurements. Studies by the principal investigator (PI) will utilize variable temperature, variable field magnetic circular dichroism to determine the strength of the magnetic coupling in a series of carboxylate-bridged Co(II) dimer complexes and enzyme active sites which contain dinuclear Co(II). This will provide a more detailed picture of the electronic ground state structure of this active site motif commonly found in nature. MCD will be used by the co-PI to perform exploratory experiments on the interactions of Ru(III) complexes with DNA analogues. Two additional Middlebury biochemistry professors will use the instrument to collect CD data for protein secondary structure analysis.A circular dichroism spectropolarimeter will produce circular dichroism spectral data that provides information on molecular structure and especially the conformations of biomolecules such as proteins, enzymes and nucleic acids. In magnetic circular dichroism, chirality is induced by a strong magnetic field applied parallel to the direction of light propagation, a phenomenon known as the Faraday effect. The behavior of MCD intensity with temperature and field strength is dependent on the electronic ground state of the metal. Thus MCD is a sensitive probe of the electronic structure associated with paramagnetic metals ions in small complexes and protein active sites. The instrument will be used in research by undergraduate students. This training will prepare students to utilize this sophisticated technique in various careers, especially in chemical, biological and health related fields.