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.

了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贡献至关重要 来了解蛋白质的作用机制。我们希望检查以下影响： 金属类型、配体和远程残基的改变对金属 配体的键强度、几何形状以及与底物的反应性 金属蛋白的活性位点。为此，我们将重点关注两方面 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SOD中， 对酶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。我们将比较键合和反应 不同SOD中的途径以及替换金属位点的效果 与其他过渡元素，以及远程改变的影响 活性位点上的残留物。金属抗体查询将 专注于各种过渡金属结合的特异性 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 抗荧光素抗体并比较其结合和反应性 锌和铜的衍生物。这项工作随后将扩展到 其他可以引入的潜在金属酶活性位点 抗体，研究金属替代的影响 提高金属抗体的催化功能。 这项工作中使用的技术将结合密度 功能计算和静电模型。的能量学 金属与近配位环境中的配体相互作用 用量子力学密度泛函方法计算，并且 结果将与静电描述结合起来 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影响 结合可以从允许的电子结构详细导出 量子力学分析，而改变的间接影响 远程残基，如定点诱变或 可以有效地包括由于 pH 变化而引起的质子化/去质子化。