KINETICS OF NITRIC OXIDE BINDING TO HEMOPROTEINS

无细胞血红蛋白的血管内给药似乎 与肺和全身血压的升高密切相关。 这种高血压反应归因于 血红蛋白和内皮源性舒张因子（EDRF）， 现在认为是一氧化氮（NO）。 我们探索了 NO和一些化学修饰的氧化形式之间的关系 血红蛋白 这些血红蛋白是血液替代品的候选者， 它们的四聚体的较低的氧亲和力和较大的稳定性， 结构. 使用快速反应技术，停止流动装置， 我们记录到，在初始NO的速率上存在差异， 结合这些蛋白质的铁形式，并在随后的NO- 驱动还原步骤。由于NO将氧合血红蛋白氧化为高铁血红蛋白 （metHb）在体内非常迅速，我们假设氧化还原循环 NO和高铁血红蛋白之间的关系可能是部分原因， NO作为生物换能器，导致血管张力改变， 对于不同的血红蛋白制剂观察到不同的影响。工作是 正在进行中，以探索NO与其他物质相互作用的机制。 为了充分了解血红素口袋 化学和其他结构特征决定了NO与 血红素蛋白 在这方面，我们开始研究稳态和 NO反应的瞬态动力学与简单和更复杂的 血红素蛋白如肌红蛋白和过氧化氢酶。 我们也 探索过氧亚硝酸盐（OONO-）的反应性， 与超氧离子的氧化物反应，这被认为是在 血管壁 这将最终有助于设计 血红蛋白沿着所需氧结合特性， 表现出抑制的与NO反应的能力。

Intravascular administration of cell-free hemoglobin appears to be strongly correlated with a rise in pulmonary and systemic blood pressure. This hypertensive response has been attributed to the reaction between hemoglobin and the endothelium-derived relaxing factor (EDRF), which is now believed to be nitric oxide (NO). We explored the interactions between NO and the oxidized forms of a number of chemically modified hemoglobins. These hemoglobins are blood substitute candidates due to their lower oxygen affinity and greater stability of their tetrameric structures. Using fast reaction techniques, the stopped flow apparatus, we documented that there are differences in the rate of the initial NO binding to the ferric forms of these proteins and in the subsequent NO- driven reduction step. Since NO oxidizes oxyhemoglobin to ferrihemoglobin (metHb) extremely rapidly in vivo, we hypothesized that a redox cycle between NO and metHb could be partially responsible for the depletion of NO as a biological transducer, leading to altered vascular tone with variable effects observed for different hemoglobin preparations. Work is in progress to explore the mechanism(s) of interactions of NO with other hemoproteins to fully understand the degree to which heme pocket chemistry and other structural features determine the binding of NO to hemoproteins. In this regard, we began to study both steady state and transient kinetics of NO reactions with simple and more complex hemoproteins such as myoglobin and catalase, respectively. We are also exploring the reactivity of peroxynitrite (OONO-), a product of nitric oxide reaction with superoxide ions, which is thought to be produced in the vascular wall. This will ultimately contribute to the design of hemoglobin that, along with desirable oxygen binding characteristics, exhibits a suppressed ability to react with NO.