ELECTRONIC STRUCTURE OF SODS AND METALLOANTIBODIES

SODS 和金属抗体的电子结构

• 批准号: 2392191
• 负责人: Louis Noodleman
• 金额: $ 14.11万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2392191
• 关键词: abzyme; active sites; antibody; chemical binding; chemical bond; chemical models; electron density; enzyme structure; metalloproteins; protein engineering; protein structure function; protonation; superoxide dismutase

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.

理解金属蛋白中金属中心的电子结构 对于理解各个组件的贡献至关重要 蛋白质的作用机制。我们希望研究一下这些影响 金属类型、配体和远程残基的变化对金属- 配体的键强度、几何构型和与底物的反应性 金属蛋白的活性部位。为此，我们将重点关注两个方面 主要领域：L)三种超氧化物歧化酶(SOD)-铁、锰、 和铜/锌，以及2)基因工程金属抗体。在超氧化物歧化酶中， 对酶的反应性有影响，这取决于 初始电子亲和势，键断裂，质子化/去质子化，As 以及其他静电力。我们将比较成键和反应 不同超氧化物歧化的途径及金属位替代的影响 与其他过渡元素的关系，以及偏远地区变化的影响 活性部位上的残留物。金属抗体调查将会 集中讨论各种过渡金属结合到 基因工程抗体中的金属结合部位。最初我们 将会看到模拟碳酸酐酶的活性部位被设计成 并比较抗荧光素抗体的结合和反应性。 锌和铜的衍生产品。这项工作随后将扩展到查看 可引入的其他潜在的金属酶活性部位 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。 这项工作中使用的技术将是密度的组合 函数计算和静电模型。人类的能量学 金属在近配位环境中与配体相互作用将 可以用量子力学密度泛函方法计算，并且 结果将与静电描述相结合 周围的蛋白质和溶剂场。这种方法的优点是 金属底物和金属氨基酸残基的直接作用 结合可以从允许的电子结构中详细推导出来 量子力学分析，而变化的间接效应 远端残基，如在定点突变或 可以有效地包含由于pH变化引起的质子化/去质子化。