Fast Kinetic Investigations of Nitric Oxide Synthase

一氧化氮（NO）参与许多生理功能，包括血管舒张、神经传递、 和免疫系统的细胞毒性作用。了解一氧化氮合酶（NOS）的NO合成， 帮助药物开发（高血压、动脉粥样硬化、糖尿病）和治疗（镰状细胞 贫血、血液代用品和败血性休克）。确定催化和调节 一氧化氮合酶的机制对于理解一氧化氮是如何产生和生理管理的， 设计针对NOS功能的治疗剂。确定了这一现象背后的分子机制， NOS对NO的调节和生理性产生是我们的研究目标。我们的目标是确定 CO、NO和62与NOS结合的动力学受 辅因子和底物。我们的假设是，底物和辅因子的结合直接影响 活性位点的反应性和可接近性。我们的理论基础是理解配体的调节 通过底物和辅因子结合的结合和血红素反应性对于理解NO是如何 生产和管理是内生的。我们将使用一个专门的多通道（200-800纳米）激光为基础的 纳秒时间分辨分光光度计，用于测量配体结合、电子转移 和参与NO合成的氧活化作为底物结合的函数， 辅因子我们的目的是：1）通过测量CO双分子复合动力学作为辅因子的函数， 相互作用，确定改变NOS反应性的辅因子结合的结构机制。 我们的假设是，辅因子的结合通过诱导构象变化来调节血红素的反应性。 变化2)通过测量重组来确定NOS如何控制NO的结合和释放 动力学作为辅因子相互作用的函数。我们的假设是，结合辅因子引起结构性 3）确定CaM调节背后的结构机制 神经元NOS。PI假设还原酶结构域中的控制元件影响酶的反应性。 活动现场。4)确定辅因子的结合如何改变对氧的反应性并改变电子 NOS的转移反应。我们的假设是，O2结合和动力学受以下因素的结合影响： 辅因子我们将研究氧结合的动力学和氧活化的形成 在Flowflash后使用纳秒多通道吸收光谱的神经元NOS（nNOS）中间体 与Oz反应的开始-与公共卫生的相关性：特定分子的知识 NO如何通过底物和辅因子的结合产生和生理管理的机制 对于理解和控制NO生理学以及理解受损的NO 生理学导致有害的健康影响。

Nitric Oxide (NO) is involved in numerous physiological functions including vasodilatation.neurotransmission, and cytotoxic actions of the immune system. Understanding NO synthesis by nitric oxide synthase (NOS) will aid in drug development (for hypertension, atherosclerosis, diabetes) and therapeutic treatments (sickle cell anemia, blood substitutes, and septic shock) that utilize NO bioactivity. Determining catalytic and regulatory mechanisms of NOS is critical for understanding how NO is produced and managed physiologically, and for designing therapeutic agents that target NOS function. Determining the molecular mechanisms behind the regulation and physiological production of NO by NOS is our research goal. Our objective is determining how the kinetics of CO, NO, and 62 binding to NOS are controlled by conformational changes induced by cofactors and substrate. Our hypothesis is that the binding of substrates and cofactors has a direct effect on the reactivity and accessibility of the active site. Our rationale is that understanding the modulation of ligand binding and heme reactivity by substrate and cofactor binding is crucial for under-standing how NO is produced and managed endogenously. We will use a specialized multichannel (200-800 nm) laser-based nanosecond time-resolved spectrophotometer to measure the fast kinetics of ligand binding, electrontransfer, and oxygen activation involved in NO synthesis as a function of the binding of substrate and cofactors. Our aims are: 1) By measuring CO bimolecular recombination kinetics as a function of cofactor interactions, determine the structural mechanism for the binding of cofactors altering the reactivity of NOS. Our hypothesis is that the binding of cofactors modulates heme reactivity by inducing conformational changes. 2) Determine how NOS controls the binding and release of NO by measuring recombination kinetics as a function of cofactor interactions. Our hypothesis is that binding cofactors causes structural changes, altering the binding kinetics of NO. 3) Determine the structural mechanism behind CaM regulation in neuronal NOS. The PI hypothesizes that control elements in the reductase domain affect the reactivity of the active site. 4) Determine how the binding of cofactors alters reactivity to oxygen and alters electron transfer reactions of NOS. Our hypothesis is that 02 binding and kinetics are influenced by the binding of cofactors. We will examine the kinetics of oxygen binding and the formation of oxygen activated intermediates in neuronal NOS (nNOS) using nanosecond multichannel absorption spectroscopy after flowflash initiation of the reaction with Oz- Relevance to Public Health: Knowledge of the specific molecular mechanisms of how NO is produced and managed physiologically by the binding of substrates and cofactors is crucial to understanding and controlling NO physiology and understanding how compromised NO physiology leads to deleterious health effects.