The Influence of Cysteinate Protonation in Nickel Containing Metalloenzymes

半胱氨酸质子化对含镍金属酶的影响

• 批准号: 9170625
• 负责人: Jason M Shearer
• 金额: $ 22.16万
• 依托单位: UNIVERSITY OF NEVADA RENO
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9170625
• 关键词: Active Sites; Amino Acids; Biochemical; Biochemical Process; Biochemical Reaction; Bioinorganic Chemistry; Chemistry; Cleaved cell; Computational Technique; Coupled; Docking; Electron Transport; Electrons; Elements; Environment; Enzymes; Geometry; Health; Helicobacter pylori; Human; Hydrogen Bonding; Hydrogen Peroxide; Investigation; Iron; Lead; Length; Ligands; Metals; Microbe; Modeling; Nature; Nickel; Optics; Process; Property; Protons; Psychological Techniques; Reaction; Research; Resources; Roentgen Rays; Running; Series; Site; Spectrum Analysis; Structure; Superoxide Dismutase; System; Thermodynamics; Ursidae Family; Work; absorption; abstracting; analog; base; computer studies; electronic structure; geometric structure; human disease; insight; interest; metalloenzyme; nickel-iron hydrogenase; novel therapeutic intervention; oxidation; pathogen; pathogenic bacteria; physical property; protonation; small molecule; tool

Project Summary. Cysteinate ligated nickel metalloenzymes are found in a number of pathogenic bacteria. Some of these nickel containing metalloenzymes, such as nickel-iron hydrogenase ([NiFe]H2ase) found in Helicobacter pylori, are found in microbes responsible for human diseases. At least two nickel containing metalloenzymes, nickel containing superoxide dismutase (NiSOD) and [NiFe]H2ase, possess a coordinated protonated cysteinate residue (Ni-S(H+)-Cys). We suspect that the Ni-S(H+)-Cys bond is involved in the enzymatic mechanism and also modulates the electronic structure and reactivity of these metalloenzymes. Our research will take advantage of functional metalloenzyme based mimics of NiSOD and small molecule mimics of [NiFe]H2ase. Metallopeptide based mimics of NiSOD that my group has prepared to date reproduce the structure and physical properties of the metalloenzyme. These metallopeptides are also catalytically active, effecting O2– disproportionation with rate constants approaching those observed in the metalloenzyme. Recent work by my group has demonstrated that these mimics facilitate O2– reduction to H2O2 via a unique proton coupled electron transfer (PCET) reaction from a Ni-S(H+)-Cys moiety to O –. We will probe this reaction by 2 preparing derivatives of these metallopeptides that will alter the fundamental nature of the PCET reaction. This will yield insight into the general scope of PCET reactions facilitated by such moieties. In addition, we will prepare metallopeptide based NiSOD mimics that more accurately replicate the enzymatic reaction mechanism. Preliminary work demonstrates that the mechanism of O2– reduction effected by the metallopeptide is distinct from NiSOD itself. By producing mimics that reproduce enzymatic reactivity we will gain a better understanding of the mechanism of O2– disproportionation effected by NiSOD itself. Also, we will investigate the influence of the Ni-S(H+)-Cys moiety on [NiFe]H2ase model compounds. We propose that the protonation of the coordinated cysteinate ligand is dramatically altering the electronic structure of the Ni-center in [NiFe]-H2ase; specifically it is reducing the hydricity of the mechanistically important Ni(III)-H intermediate biasing [NiFe]H2ase to perform H2 oxidation chemistry. This supposition will also be probed under this initiative. This research runs the gamut of tools utilized in bioinorganic chemistry. As with many of our studies synthetic, biochemical, spectroscopic, mechanistic, and computational studies will be brought to bear on understanding all aspects of the metallopeptides and small molecule mimics. The use of metalloenzyme mimics in our investigations is especially noteworthy; few studies have been performed where insight into specific biochemical processes are revealed through metallopeptide based metalloenzyme mimics. Therefore completion of this project will not only reveal interesting aspects of biologically important Ni-S(H+)-Cys moieties, but will also push the limits of investigations concerning metallopeptide based metalloenzyme mimics.

项目摘要。在许多致病细菌中发现半胱氨酸连接的镍金属酶。 其中一些含有金属酶的镍，例如在 幽门螺杆菌在负责人疾病的微生物中发现。至少两个镍包含 金属酶，含有超氧化物歧化酶（NISOD）和[Nife] H2ase的镍，具有协调 质子型半胱氨酸居住（Ni-S（H+） - Cys）。我们怀疑Ni-S（H+） - CYS键参与 酶促机理，还调节了这些金属酶的电子结构和反应性。 我们的研究将利用基于功能性金属酶的NISOD和小分子的模仿。 [Nife] H2ase的模仿。我的小组准备繁殖的基于金属肽的模仿模仿 金属酶的结构和物理特性。这些金属肽也具有催化活性， 与接近金属酶观察到的速率常数相矛盾。最近的 我的小组的工作表明，这些模仿的O2 - 通过独特的质子将其减少到H2O2 从Ni-S（H+） - Cys部分到O – o –的耦合电子转移（PCET）反应。我们将通过 2 制备这些金属肽的衍生物，这些衍生物将改变PCET反应的基本性质。这 将洞悉此类部分的PCET反应的一般范围。此外，我们将 准备基于金属肽的NISOD模拟物，更准确地复制酶促反应 机制。初步工作表明，由O2降低的机制由 金属肽与Nisod本身不同。通过产生繁殖酶促反应性的模拟物，我们将 更好地了解Nisod本身所产生的O2-违约的机制。另外，我们会的 研究Ni-S（H+） - Cys部分对[Nife] H2ase模型化合物的影响。我们建议 配位半胱氨酸配体的质子化正在动态改变Ni-Center的电子结构 在[Nife] -h2ase;特定的cally正在降低机械重要的Ni（iii）-h中间体的水性 偏置[Nife] H2ase执行H2氧化化学。该倡议也将探究这种假设。 这项研究运用了生物无机化学中使用的一系列工具。与我们的许多研究合成一样， 生化，光谱，机械和计算研究将受到理解的影响 金属肽和小分子模仿的所有方面。在我们的 调查特别值得注意。很少有研究洞察特定的研究 生化过程通过基于金属肽的金属酶模拟物揭示。所以 该项目的完成不仅会揭示生物学上重要的Ni-S（H+）-CYS的有趣方面 部分，但也将推动有关基于金属肽的金属酶的调查限制 模仿。