ELECTRONIC STRUCTURE OF SODS AND METALLOANTIBODIES

SODS 和金属抗体的电子结构

• 批准号: 2187787
• 负责人: Louis Noodleman
• 金额: $ 12.67万
• 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 1998-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2187787
• 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的电子结构