ELECTRONIC STRUCTURE OF SODS AND METALLOANTIBODIES

理解金属蛋白中金属位点的电子结构 对于理解各个组成部分的作用至关重要 蛋白质的作用机制我们希望研究 金属类型、配体和远程残基的改变对金属- 配体键强度、几何形状和与基质的反应性， 金属蛋白的活性部位。为此，我们将重点关注两个 主要领域：1）三种超氧化物歧化酶（SOD）--铁，锰， 和铜/锌，和2）基因工程金属抗体。在SOD中， 对酶的反应性的影响取决于 初始电子亲和力、键断裂、质子化/去质子化，如 以及其他静电力。我们将比较成键和反应 不同SOD中的途径以及替换金属位点的影响 与其他过渡元素，以及远程的变化的影响， 活性位点上的残基。金属抗体调查将 专注于各种过渡金属与 抗体中的基因工程金属结合位点。最初我们 将研究碳酸酐酶的活性位点模拟物， 抗荧光素抗体的结合和反应性进行比较， 锌和铜衍生物。这项工作将扩大到看看 可以引入其它潜在的金属酶活性位点， 抗体，研究金属替代的影响，着眼于 提高金属抗体的催化功能。 在这项工作中使用的技术将是密度的组合 功能计算和静电模型。的能量学 在近配位环境中与配体相互作用的金属将 用量子力学密度泛函方法计算， 结果将与静电描述的 周围的蛋白质和溶剂场。这种方法的优点 金属-底物和金属-氨基酸残基的直接作用 结合可以详细地从电子结构中推导出来， 量子力学分析，而改变的间接影响， 远程残基，如在定点诱变或 由于pH变化，质子化/去质子化可以有效地包括在内。

Understanding the electronic structure of metal sites in metalloproteins is crucial to understanding the contributions of the individual components to the protein's mechanism of action. We wish to examine the effects that alterations in metal types, ligands, and remote residues have on metal- ligand bond strengths, geometries, and reactivities with substrates in the active sites of metalloproteins. Toward this end, we will focus on two major areas: l) the three superoxide dismutases (SODs)----iron, manganese, and copper/zinc, and 2) genetically engineered metalloantibodies. In SOD, there are effects on the reactivity of the enzyme that depend on the initial electron affinity, bond cleavage, protonation/deprotonation, as well as other electrostatic forces. We will compare bonding and reaction pathways in the different SODs and the effect of replacing the metal sites with other transition elements, and the effects of alterations of remote residues on the active sites. The metalloantibody inquiries will concentrate on the specificity of binding of various transition metals to genetically engineered metal-binding sites in antibodies. Initially we will look at the active site mimic of carbonic anhydrase engineered into the antifluorescein antibody and compare the binding and reactivity of the zinc and copper derivatives. This work will then be expanded to look at other potential metalloenzyme active sites that can be introduced to antibodies, studying the effects of metal substitution with an eye toward improving the catalytic function of the metalloantibodies. The techniques used in this work will be a combination of density functional calculations and electrostatic models. The energetics of the metal interacting with ligands in the near-coordination environment will be calculated with quantum mechanical density functional methods, and the result will be incorporated with an electrostatic description of the surrounding protein and the solvent field. The advantage of this approach is that the direct effects of metal-substrate and metal-amino acid residue binding can be derived in detail from the electronic structure allowed by quantum mechanical analysis, while the indirect effect of alteration of remote residues, as in site-directed mutagenesis or protonation/deprotonation due to pH change, can be included efficiently.