Mechanisms of Biological Nitrosation from Nitric Oxide

描述（由申请人提供）：一氧化氮（一氧化氮，NO）在体内会发生氧化，导致产生反应性物质，形成含氮氧化物的加合物、氧化的细胞成分或相对不反应的含氧阴离子。 在NO的生物学作用中，亚硝化（单电子氧化物质亚硝基（NO+）的化学反应）在历史上（毫无疑问）在化学病理学方面受到了最多的关注。 亲核细胞靶标的亚硝化导致两种损伤（例如，亚硝胺形成和DNA碱基脱氨基作用）以及可能的调节作用（亚硝基硫醇的形成）。 然而，亚硝化在细胞中发生的机制尚不清楚。 我们的总体目标是确定NO亚硝化的生化机制。为了实现这一目标，我们将在这两个领域以前工作的基础上，沿着沿着两条路线（包括我们的四个具体目标）进行。 在目标I-II中，我们将描述NO与O2在疏水环境如膜内反应的动力学和机理特征。 我们以前曾提出，这是生物学上的主要网站为这个反应，产生强大的亚硝基物种。 我们将确定这种效应的动力学特征，我们估计在生物条件下，这种效应加速了NO/O2反应约300倍。 此外，我们将研究这种分区的机械效应，特别是，溶剂化和碰撞效应，膜双层的疏水内部可能会影响这些小的不带电的自由基物种之间的反应（而不是在水溶液中的反应）。 在目标III-IV中，我们将描述NO的非红细胞O2依赖性消耗的特征，这是在血管腔外发生的NO的定量主要转化，并且我们已经显示了亚硝酸盐（亚硝化化学的标志物）产生的结果。 这种现象与目标I-II中的膜效应不同，我们将确定这种反应的生化机制，包括涉及的细胞物种和负责NO氧化的氧物种（双氧或超氧化物）的性质以及过渡金属离子的参与。 我们还将描绘从外源性和内源性NO的亚硝化细胞化学。这些研究将提供新的见解NO及其衍生物的基本生物化学，也可能提供新的可能途径，在各种病理条件下，包括致癌作用，炎症刺激，和氧化应激的治疗发展。

DESCRIPTION (provided by applicant): Nitric oxide (nitrogen monoxide, NO) is subject to oxidation in vivo, which results in the production of reactive species that either form nitrogen oxide-containing adducts, oxidized cellular components, or relatively unreactive oxyanions. Among the biological actions of NO, nitrosation (the chemistry of the one-electron oxidized species nitrosonium (NO+)) has historically (and undoubtedly) received the most attention in terms of chemical pathology. Nitrosation of nucleophilic cellular targets results in both damaging (e.g., nitrosamine formation and DNA base deamination) and also possible regulatory effects (formation of nitrosothiols). However, the mechanism(s) whereby nitrosation takes place in cells is unknown. Our overall objective is to define the biochemical mechanism(s) of nitrosation from NO. To accomplish this objective, we will proceed along two lines (encompassing our four Specific Aims), based on our previous work in these two areas. In Aims I-II, we will delineate the kinetic and mechanistic characteristics of the reaction of NO with O2 within hydrophobic environments such as membranes. We have previously proposed that this is the major site biologically for this reaction that produces potent nitrosating species. We will determine the kinetic characteristics of this effect, which we have estimated accelerates the NO/O2 reaction by a factor of approximately 300-fold under biological conditions. In addition, we will examine the mechanistic effects of this partitioning, specifically, the solvation and collisional effects which the hydrophobic interior of membrane bilayers may have in influencing these reactions between small uncharged radical species (as opposed to reactions in aqueous solution). In Aims Ill-IV, we will delineate the characteristics of non-erythroid cellular O2-dependent consumption of NO, which is quantitatively the major transformation of NO that occurs outside the vascular lumen, and which we have shown results in the production of nitrite (a marker for nitrosative chemistry). This phenomenon is distinct from the membrane effect in Aims I-II, and we will identify the biochemical mechanism(s) of this reaction, including the cellular species involved and nature of the oxygen species responsible for NO oxidation (dioxygen or superoxide) as well as the involvement of transition metal ions. We will also delineate the nitrosative cellular chemistry from both exogenous and endogenous NO. These studies will provide both new insight into the basic biochemistry of NO and its derivatives, and also potentially provide new possible avenues for therapeutic development in a variety of pathological conditions, including carcinogenesis, inflammatory stimulation, and oxidative stress.