STRUCTURE/FUNCTION OF S-NITROSOHEMOGLOBIN

这个项目的长期目标是提高我们对血红蛋白(Hb)依赖NO的氧气转运功能的理解。在肺中，NO在氧合时与Hb的硫醇结合(R构象)，而(S)NO基团在脱氧时在外周释放(T结构)。因此，变构控制的Hb释放的NO参与了外周血流量的调节。然而，关于NO如何影响Hb的功能行为，即其O2结合和变构性质，或者NO对肺血管张力或局部呼吸-灌流关系(V/Q)的影响，人们知之甚少，所有这些都是对组织氧合的关键影响。将检验以下假设：1)亚硝化可以通过增加O2亲和力或通过促进外围O2的释放(即分别通过结合硫醇或血红素来增强R或T结构)以有意义的方式影响Hb的协同性质。(2)S-亚硝血红蛋白(SnO-Hb)对肺血管张力和V/Q匹配的影响依赖于氧分压。3)对SNO-Hb和硝基Hb的结构和功能行为的进一步了解可以用来测量人类血液中的这些物种。最终，这些研究将有助于更好地了解NO和蛋白质之间的功能调节相互作用，Hb的呼吸功能，以及对肺血管张力的O2依赖控制。我们的结果也可能对新生儿的疾病状态，如败血症、镰状细胞性贫血和持续性肺动脉高压，以及在治疗环境中，如使用吸入性NO，氧气输送和Hb功能改变的情况下有影响。

The long-term goal of this project is to improve our understanding of the NO-dependent O2 transport functions of hemoglobin (Hb). In the lung, NO binds to the thiol of Hb upon oxygenation (R conformation), and the (S)NO group is released in the periphery upon deoxygenation (T structure). Thus, allosterically-controlled NO release from Hb participates in the regulation of peripheral blood flow. However, very little is known of how NO affects the functional behavior of Hb, i.e., its O2 binding and allosteric properties, or what effect NO has on pulmonary vascular tone or regional ventilation-perfusion relationships (V/Q), all of which critically influence tissue oxygenation. The following hypotheses will be tested: 1) That nitrosylation can affect the cooperative properties of Hb in a meaningful way, either by increasing O2 affinity or by facilitating O2 release in the periphery (i.e., by reinforcing the R or T structures through binding thiols or hemes, respectively). 2) That the effects of S-nitrosohemoglobin (SNO-Hb) on pulmonary vascular tone and V/Q matching are dependent on the PO2. 3) That an improved understanding of the structure and the functional behavior of SNO-Hb and nitrosylHb can be used to make measurements of these species in human blood. Ultimately, these studies should lead to a better understanding of the function-regulating interactions between NO and protein, the respiratory functions of Hb, and the O2-dependent control of pulmonary vascular tone. Our results may also have implications in disease states such as sepsis, sickle cell anemia, and persistent pulmonary hypertension of the newborn, and in therapeutic settings such as the use of inhaled NO, where O2 delivery and Hb functions are altered.