The Nitric Oxide Producing Reactions of Hydroxyurea

描述(申请人提供)：羟基脲代表一种治疗镰状细胞疾病的新方法，这种疾病影响到600名非洲裔美国人中的1人。虽然羟基脲如何有益于影响镰状细胞病患者的分子机制尚不清楚，但最近的证据表明，一氧化氮(NO)在镰状细胞病的病理生理学和治疗中都发挥了作用。这项拟议研究的长期目标是彻底和清楚地了解羟基尿素产生NO的反应如何有助于羟基尿素治疗的有益效果。这一目标是基于这样一种假设，即羟基脲衍生的NO介导了羟基尿素治疗镰状细胞病的有益效果。产物分析、动力学和光谱研究将确定羟基脲在体外产生NO的机理，这将为体内反应提供相关信息。类似的研究应用于羟基脲与各种组织和纯化酶的孵育，将揭示羟基尿素在体内形成NO的机制和位置。具体地说，这些结果将区分羟基尿素在体外和体内形成NO的水解和氧化机制。此外，羟基脲衍生的NO与已鉴定的目标蛋白--可溶性鸟苷环化酶和无细胞血红蛋白的反应程度将通过光谱方法和产物分析确定这些反应的酶活化程度、最终反应产物和反应动力学来证明。这些结果将表明羟基脲或羟基脲衍生的NO影响或与这些靶蛋白反应的能力，并为羟基脲处理的有益效果的机制提供证据。通过化学合成，将制备独特的羟基脲类NO递送系统和水溶性氮氧基供体。这些化合物释放NO的能力将通过光谱和循环伏安研究来确定，这些结果将揭示这些新系统作为NO或氮氧基供体的能力。这些新化合物还将被评估它们刺激可溶性鸟苷环化酶并与游离细胞血红蛋白反应的能力。总之，这些结果将提供有关羟基尿素作用机制的重要信息，可用于进一步开发更好的镰状细胞治疗方法。

DESCRIPTION (provided by applicant): Hydroxyurea represents a new treatment for sickle cell disease, a condition that affects 1 in 600 Americans of African descent. While the molecular mechanisms of how hydroxyurea beneficially affects sickle cell disease patients remain unknown, recent evidence indicates a role for nitric oxide (NO) in both the pathophysiology and treatment of sickle cell disease. The long-term goal of the proposed research is to thoroughly and clearly understand how the NO producing reactions of hydroxyurea contribute to the beneficial effects of hydroxyurea therapy. This goal is based upon the hypothesis that hydroxyurea-derived NO mediates the beneficial effects of hydroxyurea therapy in sickle cell disease. Product analysis, kinetic and spectroscopic studies will determine the mechanism of in vitro NO production from hydroxyurea, which should provide relevant information to the in vivo reaction. Similar studies applied to the incubation of hydroxyurea with various tissues and purified enzymes will reveal both the mechanism and site of in vivo NO formation from hydroxyurea. Specifically, these results will distinguish between hydrolytic and oxidative mechanisms of both in vitro and in vivo NO formation from hydroxyurea. In addition, the extent of the reaction of hydroxyurea-derived NO with the identified target proteins, soluble guanylate cyclase and cell-free hemoglobin, will be demonstrated by determining the extent of enzyme activation and the ultimate reaction products and kinetics of these reactions using spectroscopic methods and product analysis. These results will indicate the ability of hydroxyurea or hydroxyurea derived-NO to influence or react with these target proteins and provide evidence for a mechanism for the beneficial effects of hydroxyurea treatment. Unique hydroxyurea-based NO delivery systems and water-soluble nitroxyl donors will be prepared through chemical synthesis. The ability of these compounds to release NO will be determined using spectroscopic and cyclic voltammetric studies and these results will reveal the ability of these new systems to act as NO or nitroxyl donors. These new compounds will also be evaluated for their ability to stimulate soluble guanylate cyclase and react with cell free hemoglobin. Together, these results will provide important information regarding the mechanism of action of hydroxyurea that can be applied to the further development of superior sickle cell treatments.