HNO Interactions with Metalloproteins: Structures and Mechanisms

说明(申请人提供)：HNO在许多生物学过程中发挥重要作用，如血管松弛、酶活性调节和神经功能调节。它还为心力衰竭和中风等疾病提供了一种很有前途的新疗法。金属蛋白会产生许多HNO生物效应。然而，原子水平的结构和功能信息在很大程度上是未知的。我们的长期目标是确定HNO如何与其生物靶标结合，以及这种结合如何导致蛋白质功能反应。目的1是确定肌红蛋白(Mb)中HNO的原子水平结合模式。血红素蛋白经常参与HNO的结合。但没有任何HNO蛋白质复合体的X射线结构。第一个稳定的HNO络合物是与Mb形成的，这使得我们能够进行大量的光谱表征，最近我们通过计算工作提出了两个新的活性中心模型。这些模型表现出独特的新特征，需要用蛋白质水平的研究来验证。我们的初步蛋白质水平研究支持我们的活性部位结果，但也提供了对附近群体影响的更多细节。我们将进行各种结合模式的蛋白质水平的研究，并与更多以前没有研究过的实验结果进行比较，以提供第一张严格的原子水平的HNO与Mb的结合图。这些结果将有助于研究HNO与其他血红素蛋白的结合。目的二是通过铜、锌-超氧化物歧化酶和具有成像功能的铜配合物来确定HNO/NO的转化机制。HNO与铜、锌-超氧化物歧化酶的反应在体内NO的形成中起重要作用。最近有报道称，一种铜配合物也有类似的反应，可以选择性地检测和成像HNO。我们的初步研究为它们找到了有趣的反应途径。我们将使用不同尺度的活性部位模型和蛋白质环境来研究反应，以帮助理解它们对机制的影响。将对具有修饰配体的铜配合物进行更多的机理研究，以提供HNO显像剂的设计指南。目的3是通过Mb确定HNO/NO的转化机制。我们的初步研究显示了一些有趣的反应机理来支持实验结果。我们将进行一系列的计算研究，包括蛋白质水平的计算，以验证这些机制。由于血红素模型最近被用来捕获HNO，我们还将系统地评估金属中心和血红素配体的作用，以帮助未来HNO清除剂的设计。这些结果将提供有用的HNO与金属蛋白和模型相互作用的结构和机制结果，以促进与HNO有关的健康、疾病和治疗治疗的研究。

DESCRIPTION (provided by applicant): HNO plays significant roles in many biological processes, such as vascular relaxation, enzyme activity regulation, and neurological function regulation. It also offers a promising new treatment for diseases such as heart failure and stroke. Many HNO biological effects occur with metalloproteins. However, the atomic level structural and functional information are largely unknown. Our long-term goal is to determine how HNO binds with its biological targets and how such binding leads to protein functional responses. Aim 1 is to determine the atomic level HNO binding modes in myoglobin (Mb). Heme proteins are frequently involved in HNO binding. But there are no X-ray structures of any HNO protein complexes. The first stable HNO complex is with Mb, enabling numerous spectroscopic characterizations, which were used by us recently with computational work to propose two novel active site models. These models exhibit unique novel features, which need to be validated with protein level investigations. Our preliminary protein level studies has shown support of our active site results, but also offered more details of effects on nearby groups. We will perform protein level investigations of various binding modes and compare with more experimental results not investigated before, to provide the first rigorous atomic level HNO binding picture with Mb. Results will facilitate investigations of HNO binding with other heme proteins. Aim 2 is to determine HNO/NO conversion mechanism via Cu,Zn-SOD and a Cu complex with imaging function. Reaction of HNO with Cu,Zn-SOD was suggested to be important for in vivo formation of NO. A copper complex was recently reported to have similar reaction and allow selective detection and imaging for HNO. Our preliminary studies found interesting reaction pathways for them. We will study reactions using different scales of active site models and protein environment to help understand their effects on mechanisms. Additional mechanistic investigations of the Cu complex with modified ligands will be done to provide design guidelines for HNO imaging agents. Aim 3 is to determine HNO/NO conversion mechanisms via Mb. Our preliminary studies showed some interesting reaction mechanisms to support experimental results. We will perform a series of computational investigations including protein level calculations to validate the mechanisms. As heme models were recently used to trap HNO, we will also systematically evaluate effects of metal centers and heme ligands to help future design of HNO scavengers. Results will provide useful structural and mechanistic results of HNO interactions with metalloproteins and models to facilitate studies of health, diseases, and therapeutic treatments involving HNO.