Biological redox chemistry underlying nitric oxide and hydrogen peroxide signaling

我们正在研究过氧化氢(H2O2)和一氧化氮(NO)等氧化还原活性小分子如何与金属蛋白和其他生物分子相互作用，以控制细胞的功能。过量的过氧化氢会损害细胞，并导致细胞程序性死亡(凋亡)，涉及到血红素蛋白，细胞色素c。我们对触发这一事件的详细化学过程感兴趣，因为控制细胞凋亡的能力在中风和癌症的治疗中是非常必要的。在正常情况下，细胞内的过氧化氢水平受到严格控制。由于其易于遗传操作，我们正在使用面包酵母来寻找新的过氧化氢传感和信号传递的分子机制。我们的重点是血红素酶，细胞色素c过氧化物酶(CCP)，它可以通过催化过氧化氢还原为水来解毒。我们正在研究产生CCP突变或根本不产生CCP的转基因酵母菌株。我们还对纯化的CCP及其突变体进行了体外研究，以更好地了解其在体内的作用方式。这项工作的目标是获得关于有机体如何对富氧环境中发生的氧化还原挑战做出快速反应的化学见解。氧化应激是导致衰老和老年性疾病的主要因素。一氧化氮(NO)影响血液流动、神经信号转导和免疫反应等关键生物学功能。我们想了解NO如何对蛋白质和激素进行化学修饰，从而对它们的作用模式产生深远的影响。例如，蛋白质硫醇的可逆S亚硝化是细胞信号的一种主要形式，我们实验室的研究重点是促进硫醇之间NO转移的金属催化过程。我们还在探索NO的单电子还原产物硝基(HNO)的化学反应。拟议的研究将增加我们对NO生物无机化学的了解，这对于理解心血管疾病和神经退行性变的分子基础至关重要。

We are investigating how small, redox-active molecules such as hydrogen peroxide (H2O2) and nitric oxide (NO) interact with metalloproteins and other biomolecules to control the functioning of cells. Excess H2O2 can harm cells and cause programmed cell death (apoptosis) involving the heme protein, cytochrome c. We are interested in the detailed chemical processes that trigger this event since an ability to control apoptosis is highly desirable in the treatment of stroke and cancer. Under normal conditions, cellular H2O2 levels are tightly controlled. Because of its ease of genetic manipulation, we are using baker's yeast in our search for new molecular mechanisms of H2O2 sensing and signaling. Our focus is the heme enzyme, cytochrome c peroxidase (CCP), which can detoxifiy H2O2 by catalyzing its reduction to H2O. We are investigating genetically modified yeast strains that produce CCP mutants or no CCP at all. We also study purified CCP and its mutants in vitro to better understand its mode of action in vivo. The goal of this work is to obtain chemical insight into how organisms respond rapidly to redox challenges that occur in an oxygen rich environment. Oxidative stress is a major contributing factor in aging and in age-related diseases.Nitric oxide (NO) influences key biological functions such as blood flow, neuronal signaling and the immune response. We would like to understand how NO chemically modifies proteins and hormones, which can have profound effects on their mode of action. For example, reversible S-nitrosation of protein thiols is a major form of cell signaling, and research in our laboratory focuses on metal-catalyzed processes that promote NO-transfer between thiols. We are also probing the chemical reactions of the one-electron reduction product of NO, nitroxyl (HNO). The proposed studies will increase our knowledge of the bioinorganic chemistry of NO, which is critical in understanding the molecular underpinnings of cardiovascular disease and neurodegeneration.