Thermodynamics of Metal-Protein Interactions

化学部生命过程化学项目将资助达特茅斯学院的Dean Wilcox博士定量描述金属离子与蛋白质结合的热力学。这项研究将在a)金属离子对蛋白质稳定性的贡献，以及b)蛋白质对结合金属离子的氧化还原性质的调节方面提供见解。主要使用微量热法和对蛋白质(位点特定突变)和金属(例如，等结构的锌、钴、镉)的系统扰动，将量化金属结合的焓和熵分量，以及金属和蛋白质对金属蛋白稳定性的贡献。此外，将通过确定溶剂对金属与蛋白质结合的热力学的影响来评估溶剂化对金属-蛋白质相互作用的贡献。在这些方法的新应用中，当金属离子处于两种氧化状态时，将确定金属与蛋白质结合的热力学，并将量化受蛋白质调节的金属还原电位的焓和熵分量。在活体生物中，必需的痕量金属通常与蛋白质结合。金属发挥着关键的作用，包括结构作用，其中金属(通常是锌)帮助稳定蛋白质的活性形式，以及在基本反应中的催化作用，在基本反应中，蛋白质调节金属(如铜)的化学性质。无论是金属对蛋白质的稳定作用，还是蛋白质对金属离子性质的影响，都将用Wilcox和他的学生开创的实验方法和分析来量化。这项拟议的研究将寻求洞察所谓的结构金属在蛋白质中的流行度、位置和重要性；这种洞察力可能会指导将金属离子工程到治疗性蛋白质中，以提高稳定性。相反，识别影响结合金属性质的蛋白质的特征将有助于我们理解自然如何控制和利用金属的独特反应。从事这个项目的学生在无机、物理化学和生物化学之间的界面上获得广泛的知识，并学习对科学和教育事业非常重要的技能。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Dean Wilcox from Dartmouth College to quantitatively characterize the thermodynamics of metal ion binding to proteins. This research will provide insight in a) the contributions of metal ions to the stability of proteins, and b) the modulation by the proteins of the redox properties of bound metal ions. Using primarily microcalorimetry methods and systematic perturbations of the protein (site specific mutations) and of the metal (e.g., isostructural Zn2+, Co2+, Cd2+), the enthalpic and entropic components of the metal binding will be quantified, as will be the metal and the protein contributions to the stability of the metalloprotein. Additionally, the contribution of solvation to metal-protein interactions will be evaluated by determining solvent effects on the thermodynamics of metal binding to the protein. In a novel application of these methods, the thermodynamics of metal binding to a protein will be determined when the metal ions is in two oxidation states, and the enthalpic and entropic components of the metal reduction potential, which is modulated by the protein, will be quantified.Essential trace metals are normally bound to proteins in living organisms. The metals play crucial roles, including a structural role, where the metal (often zinc) helps to stabilize the active form of a protein, and a catalytic role in essential reaction, where the protein tunes the chemical properties of a metal (such as copper). Both the stabilization of a protein by a metal and the influence by a protein of the properties of metal ion will be quantified with experimental methods and analysis pioneered by Wilcox and his students. The proposed research will seek insight in the prevalence, placement and importance of so-called structural metals in proteins; this insight may guide the engineering of metal ions into therapeutic proteins for enhanced stability. Conversely, the identification of the features of a protein that influence the properties of a bound metal will help us to understand how Nature controls and uses the unique reactions of metals. Students working on this project gain extensive knowledge at the interface between inorganic, physical and biochemistry and learn skills important for careers in science and education.