New Direction in Nuclear Magnetic Resonance of Copper and Zinc Ions in Biological Systems

生物系统中铜和锌离子核磁共振的新方向

• 批准号: RGPIN-2018-04030
• 负责人: Stachura, Monika
• 金额: $ 2.11万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712718
• 关键词: New; Direction; Nuclear; Magnetic; Resonance

Metals and their ions are indispensable for life, and as such more than one third of all proteins in biological systems require the presence of metal ions to function. Several transition elements, including copper (Cu) and zinc (Zn), have been proven to be essential for humans, and occur in the body at trace amounts (mg to g). Cu and Zn are both necessary for life, but toxic in excess, and therefore their homeostasis has to be tightly controlled. In order to understand the role of Cu and Zn in the body, it is of profound importance to understand the binding chemistry and the coordination environment that these two metal ions adopt in their biological context. Unfortunately, the absence of convenient physical and spectroscopic properties to study the local structure and dynamics at the metal sites has so far held back a detailed understanding of Cu(I) and Zn(II) biochemistry. Nuclear magnetic resonance (NMR) spectroscopy is probably the most powerful single technique to explore the structure and dynamics of molecules in solution, and therefore, it contributes fundamentally to the advancement of biological sciences. In practice, however, NMR suffers from poor sensitivity for several elements across the periodic table, including both Cu(I) and Zn(II), mainly because of the low gyromagnetic ratio of their NMR-active stable isotopes and intrinsically small signal-to-noise ratio. Furthermore, both nuclei are quadrupolar (spin > 1/2), leading to resonance lines widths in the kHz range or beyond detectability, which makes it inadequate for many frontier scientific applications. As a result, only a very few solution-phase NMR studies on Cu(I) and Zn(II)-containing biological systems can be found in the literature. This proposal seeks funds to investigate the coordination chemistry of Cu(I) and Zn(II) metal-binding sites directly in several metal ion complexes and metalloproteins using the newly established liquid-phase beta-detected NMR (beta-NMR) spectroscopy. Beta-NMR employs radioisotopes rather than stable isotopes, and it allows for measuring NMR signals by detecting the beta particles emitted by polarized, radioactive ions. It offers 1010 enhancement in sensitivity as compared to conventional NMR spectroscopy, and it can be applied to many elements across the periodic table, including both Cu(I) and Zn(II). For the past 2-3 years, TRIUMF has been working on the design and implementation of the liquid-phase beta-NMR spectrometer at the ISAC-I facility at TRIUMF, Canada. Testing is now completed using Mg-31, unambiguously establishing that beta-NMR is capable of measuring high-quality NMR resonances with resolution better than conventional Mg-25 NMR, using as few as 107 Mg ions in 2-3 L of liquid solution, and within less than an hour. Given the recent accomplishments, we are now well poised to conduct pioneering beta-NMR measurements on different Cu(I) and Zn(II) binding biological systems.

金属及其离子对于生命是不可或缺的，因此生物系统中超过三分之一的蛋白质需要金属离子的存在才能发挥作用。包括铜 (Cu) 和锌 (Zn) 在内的多种过渡元素已被证明对人体至关重要，并且在体内的含量为微量（毫克至克）。铜和锌都是生命所必需的，但过量时有毒，因此必须严格控制它们的稳态。为了了解铜和锌在体内的作用，了解这两种金属离子在其生物学背景下的结合化学和配位环境具有非常重要的意义。不幸的是，迄今为止，缺乏方便的物理和光谱特性来研究金属位点的局部结构和动力学，阻碍了对 Cu(I) 和 Zn(II) 生物化学的详细了解。 核磁共振 (NMR) 光谱可能是探索溶液中分子结构和动力学的最强大的单一技术，因此，它对生物科学的进步做出了根本性的贡献。然而，在实践中，NMR 对周期表中的几种元素（包括 Cu(I) 和 Zn(II)）的灵敏度较差，这主要是因为它们的 NMR 活性稳定同位素的旋磁比较低，并且本质上信噪比较小。此外，两个原子核都是四极的（自旋> 1/2），导致共振线宽度在kHz范围内或超出可检测范围，这使得它不足以满足许多前沿科学应用。因此，文献中关于含 Cu(I) 和 Zn(II) 的生物系统的溶液相 NMR 研究非常少。 该提案寻求资金，利用新建立的液相 β 检测核磁共振 (β-NMR) 光谱直接研究几种金属离子配合物和金属蛋白中 Cu(I) 和 Zn(II) 金属结合位点的配位化学。 Beta-NMR 使用放射性同位素而不是稳定同位素，它可以通过检测极化放射性离子发射的 β 粒子来测量 NMR 信号。与传统 NMR 光谱相比，它的灵敏度提高了 1010，并且可应用于周期表中的许多元素，包括 Cu(I) 和 Zn(II)。在过去的 2-3 年里，TRIUMF 一直致力于加拿大 TRIUMF ISAC-I 设施的液相 β-NMR 波谱仪的设计和实施。使用 Mg-31 的测试现已完成，明确表明 β-NMR 能够测量高质量的 NMR 共振，其分辨率优于传统的 Mg-25 NMR，在 2-3 L 液体溶液中使用少至 107 个 Mg 离子，并且在不到一小时的时间内完成。鉴于最近取得的成就，我们现在已准备好对不同的 Cu(I) 和 Zn(II) 结合生物系统进行开创性的 β-NMR 测量。