RUI: Determination of Magnetic Exchange Coupling in Carboxylate-Bridged Binuclear Co(II) by Magnetic Circular Dochroism

米德尔伯里学院化学系James Larrabee博士在化学系无机、生物无机和有机金属化学项目的支持下，利用变场、变温度磁圆二色性（VTVH MCD）测定了一系列羧酸盐桥接双核Co（II）配合物中的磁交换偶联J。最终目标是开发VTVH MCD作为监测双核Co（II）酶与底物、底物类似物和/或抑制剂相互作用时活性位点变化的工具。研究人员将研究一系列双核Co（II）模型化合物，以确定决定j值大小的因素。然后研究大肠杆菌中的甲硫基氨基肽酶、Co(II)-取代氰菊酯和Co(II)-取代氨基肽酶，它们都含有一个羧基桥接的双核Co（II）位点。最后，将尝试模型复合物和酶之间的相关性，以确定J的大小是否在酶的功能中起作用，以及J的变化是否可以用来探测酶的功能。羧基桥接双金属活性位点是蛋白质和酶中常见的结构基序。本研究旨在开发一种新的工具，VTVH MCD，来研究这些金属位点在生物系统中的作用。此外，它将加深对影响Co（II）离子之间相互作用强度的因素的理解，这可能与分子磁性有关。这项研究将在以本科生为主的米德尔伯里学院进行。这种类型的研究经验将鼓励本科生追求科学事业。

Dr. James Larrabee, Chemistry Department, Middlebury College, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division to determine the magnetic exchange coupling, J, in a series of carboxylate bridged binuclear Co(II) complexes using variable-field, variable temperature magnetic circular dichroism (VTVH MCD). The ultimate goal is to develop VTVH MCD as a tool to monitor changes in the active sites of binuclear Co(II) enzymes that occur when they interact with substrates, substrate analogs and/or inhibitors. A series of binuclear Co(II) model compounds will be investigated to determine the factors that determine the magnitude of J. The enzymes methionyl aminopeptidase from E. coli, Co(II)-substituted hemerythrin, and Co(II)-substituted aminopeptidase, each of which contains a carboxylatebridged binuclear Co(II) site, will then be examined. Ultimately, correlations between the model complexes and the enzymes will be attempted in order to ascertain if the magnitude of J plays a role in the function of the enzyme and if changes in J can be used to probe enzyme function.The carboxylatebridged dimetallic active site is a common structural motif in proteins and enzymes. This investigation aims to develop a new tool, VTVH MCD, to investigate how these metal sites function in biological systems. In addition, it will deepen the understanding of factors that affect the strength of the interactions between Co(II) ions, which can have relevance to molecular magnetism. The research will be conducted at a predominantly undergraduate institution, Middlebury College, with undergraduate students. This type of research experience will encourage undergraduates to pursue careers in science.