HIGH OXIDATION STATE HEMOPROTEINS AND HALIDE ACTIVATION

本申请涉及进一步阐明以下化合物的化学性质： 卤化物激活过氧化物酶。 研究将侧重于定义 活性中心分子结构、电子结构和 乳过氧化物酶和氯过氧化物酶的反应特性。 重点 将被放置在核磁共振（NMR）光谱的 血红素蛋白，以及适当铁的合成和反应 卟啉模型化合物。 这项工作的重要性体现在 观察到哺乳动物过氧化物酶的主要类别发挥其 通过激活卤化物的生物合成或生物防御功能 或拟卤离子。 将特别注意阐明 乳过氧化物酶-硫氰酸盐相互作用的化学， 保护外分泌液免受细菌入侵。 同样地， 白细胞髓过氧化物酶的氯激活杀菌功能 将由微生物氯过氧化物酶模拟。 具体 目的如下：（1）乳过氧化物酶的电子结构， 将更好地定义各种氧化还原状态的氯过氧化物酶， 通过高场核磁共振技术与其他血红素蛋白的比较， 测量;（2）将探测活性位点分子结构 通过碳-13和氮-15 NMR光谱，配体（CO，NC-， SCN和异腈）结合在铁中心，（3）非血红素阴离子结合 将通过使用多核NMR方法探测位点;以及（4） 将尝试检测直接产物并辨别 过氧化物酶中卤化物和拟卤化物活化的机制， 模型血红素化合物。

This application is concerned with further elucidating the chemistry of halide-activating peroxidase enzymes. Studies will focus on defining the active site molecular structure, the electronic structure, and the reactivity properties of lactoperoxidase and chloroperoxidase. Emphasis will be placed on nuclear magnetic resonance (NMR) spectrocopy of the hemoproteins, as well as synthesis and reactions of appropriate iron porphyrin model compounds. The importance of this work is found in the observation that major classes of mammalian peroxidases exert their biosynthetic or biological defense functions through activation of halide or pseudohalide ions. Particular attention will be given to elucidating the chemistry of lactoperoxidase-thiocynate interactions, as this system functions to protect exocrine fluids from bacterial invasion. Likewise, the chloride-activating bactericidal functions of leukocyte myeloperoxidase will be modeled by the microbial chloroperoxidase enzyme. Specific objectives follow: (1) electronic structures of lactoperoxidase and chloroperoxidase in various redox states will be better defined and compared with those of other hemoproteins through high-field NMR measurements; (2) the active site molecular structure will be probed through carbon-13 and nitrogen-15 NMR spectroscopy, of ligands (CO, NC-, SCN, and isonitriles) bound at the iron center, (3) non-heme anion binding sites will be probed through use of multinuclear NMR methods; and (4) attempts will be made to detect the direct products and discern the mechanisms of halide and pseudohalide activation in the peroxidases and in model heme compounds.