CAREER: The Interaction of Nitric Oxide with Cytochrome P450

这一无机化学、生物无机和金属有机化学项目以及分子和细胞生物学项目的职业奖支持了密歇根大学的Nicolai Lehnert教授探索一氧化氮(NO)与细胞色素P450相互作用的工作。该项目的目标是获得对细胞色素P450催化的NO氧化还原转化光谱的基本见解。研究利用了细胞色素P450cam酶和合成的模型络合物。用磁圆二色谱和共振拉曼光谱确定了不同模型络合物和P450cam野生型和突变体中硫酸盐配体的相对施主强度。制备了亚铁和亚铁血红素亚硝酸酯，研究了它们的光谱性质、电子结构和反应活性与硫酸盐给电子体强度的关系。然后研究了这些亚硝基络合物的生物相关反应，特别是P450nor(NO解毒)介导的NO还原为N2O的反应，以及亚铁血红素亚硝醇与O2和超氧化物的反应(亚硝化应激)。一门关于金属在生活中的作用的新本科课程正在开发中，以吸引未被充分代表的少数族裔学生学习基础科学。这门课的重点是基本的生物和化学过程与健康、环境和替代能源等对社会有重大影响的问题之间的关系。这些领域的实践研究经验的后续项目就是为这些学生设计的。一氧化氮在生物系统中是一把双刃剑：它对许多信号和调节过程至关重要，但浓度过高时，它也对生物体构成致命威胁。阐明细胞色素P450与NO之间的基本反应对于生物化学家确定P450如何参与NO信号传递、转化和解毒的生物网络具有重要意义。特别是，预计研究中确定的NO和细胞色素P450之间的反应可能与人类生理学有关。

This CAREER award in the Inorganic, Bioinorganic and Organometallic Chemistry program and the Molecular and Cellular Biology program supports work by Professor Nicolai Lehnert at the University of Michigan to probe the interaction of nitric oxide (NO) with cytochrome P450. The goal of this project is to obtain fundamental insight into the spectrum of redox transformations of NO that can be catalyzed by cytochrome P450s. The investigations utilize both the enzyme cytochrome P450cam and synthetic model complexes. Magnetic circular dichroism and resonance Raman spectroscopy are used to establish the relative donor strengths of the thiolate ligands in different model complexes and P450cam wild type and mutants. Ferrous and ferric heme nitrosyls are prepared and their spectroscopic properties, electronic structures, and reactivities are studied as a function of the thiolate donor strength. Biologically relevant reactions of these nitrosyl complexes are then investigated, including in particular the reduction of NO to N2O as mediated by P450nor (NO detoxification) and the reaction of ferrous heme nitrosyls with O2 and superoxide (nitrosative stress). A new undergraduate course on the role of metals in life is being developed to attract underrepresented minority students to the basic sciences. The class focuses on the relation between fundamental biological and chemical processes and questions of high current impact in society like health, the environment and alternative energy sources. Follow-up programs for hands-on research experiences in these areas are designed for these students. Nitric oxide is a double-edged sword in biological systems: it is of central importance for many signaling and regulating processes, but at too high concentrations it also constitutes a deadly threat to the organism. The clarification of the fundamental reactions between cytochrome P450s and NO is of key importance for biological chemists to determine how P450s could participate in the biological network of NO signaling, transformation and detoxification. In particular, it is expected that the reactions between NO and cytochrome P450s identified in the research could potentially be relevant to human physiology.