ACTIVE SITES OF FREE RADICAL METALLOENZYMES

描述：由于容易制造而产生的自由基反应性 而破坏一个电子键会导致自由基的重要作用 在生物催化中，为基本过程提供简单的途径 如C-C键的形成和断裂、原子转移和氧化还原化学。 生物学已经进化出专门的结构来利用这一点 独特的反应性，但大多数生物自由基的不稳定性使 它们很难详细研究。惠特克的研究重点是 活性中心中一种异常稳定的自由基研究 半乳糖氧化酶，一种直接参与活性的蛋白质自由基 自由基偶联铜络合物的位置氧化还原化学。半乳糖 氧化物酶提供了一个独特的机会来研究参与 酶催化中的自由基--自由基研究的范式 催化自由基较少的其他体系中的催化作用 无障碍。这项研究计划是基于多学科的方法 结合生物化学、合成、光谱学和计算 深入了解自由基生物防治的方法 反应性。包括同位素动力学在内的机理研究将探索 质子在自由基催化中的作用。生化特性 半乳糖氧化酶和两个功能变体乙二醇氧化酶和 甘油氧化酶，将提供一个比较结构的框架 以及这些蛋白质中自由基的功能。比较解剖学 乙二醛氧化酶将通过结晶学和 野生型和突变型蛋白的机制研究。光谱学 研究(吸收、圆二色(CD)、磁性圆 二色性(MCD)、斯塔克和电子顺磁共振(EPR)将 将有关基本部首的结构信息扩展到 与化学物质的来源直接相关的电子水平 反应性。活性位铜的低温MCD实验 离子和无机模型将扩展对金属的作用的洞察 在催化作用下。这些多个实验方法将是 补充了光谱和从头计算的理论模型 催化自由基电子结构的计算 很复杂。

DESCRIPTION: Free radical reactivity resulting from the ease of making and breaking one electron bonds leads to essential roles for radicals in biological catalysis, providing easy paths for fundamental processes like C-C bond formation and cleavage, atom transfer and redox chemistry. Biology has evolved specialized structures to take advantage of this unique reactivity, but the instability of most biological radicals makes them difficult to study in detail. The Whittaker's research is focused on studies of an unusually stable free radical in the active site of galactose oxidase, a protein radical directly participating in active site redox chemistry as a free radical-coupled copper complex. Galactose oxidase has provided a unique opportunity to study the involvement of free radicals in enzyme catalysis, serving as a paradigm for radical catalysis in other systems where the catalytic free radical is less accessible. The research plan is based on a multidisciplinary approach combining biochemistry, synthesis, spectroscopy, and computational methods that give insight into the biological control of radical reactivity. Mechanistic studies including isotope kinetics will explore the role of protons in radical catalysis. Biochemical characterization of galactose oxidase and two functional variants, glyoxol oxidase and glycerol oxidase, will provide a framework for comparing the structure and function of the radicals in these proteins. The comparative anatomy of glyoxal oxidase will be developed through crystallographic and mechanistic studies on wild type and mutant protein. Spectroscopic studies (absorption, circular dichroism (CD), magnetic circular dichroism (MCD), Stark, and electron paramagnetic resonance (EPR) will extend structural information on the essential radicals to the electronic level that relates directly to the origins of chemical reactivity. Low temperature MCD experiments on the active site cupric ion and inorganic models will extend insight into the role of the metal in catalysis. These multiple experimental approaches will be complemented by theoretical modeling of the spectra and ab initio calculations of the electronic structure of the catalytic radical complex.