Structural Studies on Nitric Oxide Synthase

项目描述（由申请人提供）：本项目的长期目标是研究一氧化氮合酶（NOS）的结构-功能关系，并开发NOS异构体选择性抑制剂和药物。一氧化氮是负责一氧化氮生物合成的酶，一氧化氮是心血管和神经系统中至关重要的信号分子，也是免疫系统中的细胞毒性物质。哺乳动物有3种NOS亚型：eNOS（内皮NOS，调节血压）、nNOS（神经元NOS，神经信号传导）和iNOS（诱导NOS，免疫系统）。nNOS过度产生NO与许多神经退行性过程有关，因此，选择性阻断nNOS的药物应该具有相当大的治疗效益。选择性很重要，因为目标是阻断nNOS而不是eNOS，因为eNOS对维持适当的血管张力和血压至关重要。这是一个具有挑战性的问题，因为所有3种NOS亚型的活性位点几乎相同，并且大多数已知的NOS抑制剂没有选择性。利用晶体学、计算化学和药物化学的结合，nnos选择性化合物已经被开发、测试，并在动物模型中显示出在预防缺血性脑损伤方面非常有效。我们未来的目标是在这项初步工作的基础上进一步发展，并开发已经发现的新的可药物靶点。在结构-功能研究方面，未来的努力将集中在构象动力学上，这些构象动力学对于通过对新基因组的生物信息学搜索发现的新nos的功能和结构具有重要意义。

DESCRIPTION (provided by applicant): The long range goal of this project is to study structure-function relationships in nitric oxide synthase (NOS) and to develop isoform selective NOS inhibitors and drugs. NOS is the enzyme responsible for the biosynthesis of NO, a critically important signaling molecule in the cardiovascular and nervous systems and also is a cytotoxic agents in the immune system. Mammals have 3 NOS isoforms: eNOS (endothelial NOS, regulates blood pressure), nNOS (neuronal NOS, neural signaling), and iNOS (inducible NOS, immune system). The over production of NO by nNOS is associated with a number of neuro-degenerative processes and thus, drugs that selectively block nNOS should be of considerable therapeutic benefit. Selectivity is important since the goal is to block nNOS but not eNOS since eNOS is critical in maintaining proper vascular tone and blood pressure. This is a challenging problem since the active site of all 3 NOS isoforms are nearly identical and a majority of well known NOS inhibitors are not selective. Using a combination of crystallography, computational chemistry, and medicinal chemistry nNOS-selective compounds have been developed, tested, and shown to be very effective in preventing ischemic brain damage in animal models. Our future goals are to further build on this initial work and to exploit new druggable target sites that have been discovered. With respect to structure-function studies, future efforts will focus on conformational dynamics important for function and solving the structure of novel NOSs discovered via bioinformatic searches of new genomes. PUBLIC HEALTH RELEVANCE: This proposal centers on structure function relationships in nitric oxide synthase or NOS. NOS is the enzyme responsible of the biosynthesis of the important signaling molecule, nitric oxide (NO). The over and under production of NO is associated with a number of pathological conditions and therefore is an important drug design target.