PEROXYNITRITE, A CLOAKED OXIDANT FORMED BY NITRIC-OXIDE AND SUPEROXIDE
PEROXYNITRITE, A CLOAKED OXIDANT FORMED BY NITRIC-OXIDE AND SUPEROXIDE
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DOI：
10.1021/tx00030a017
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发表时间：
1992-11-01
影响因子：
4.1
通讯作者：
BECKMAN, JS
中科院分区：
文献类型：
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作者：
KOPPENOL, WH;MORENO, JJ;BECKMAN, JS
过氧亚硝酸盐[氧过氧硝酸盐（1-），ONOO-]可以在体内由超氧化物和一氧化氮形成。阴离子是稳定的，但酸（pK(a) = 6.8）在25℃时以1.3 s-1的速率衰变成硝酸盐。该过程的实验活化参数为DELTAH（双匕首）= +18 +/-1 kcal/mol， DELTAS（双匕首）= +3 +/- 2 cal/(mol。K)， DELTAG（双匕首）= +17 +/- 1 kcal/mol。过氧亚硝酸盐（或其质子化形式）在双分子反应中氧化一些化合物，如硫醇和硫醚。与谷胱甘肽和半胱氨酸反应的激活焓分别为10.9和9.7 kcal/mol，低于异构化反应的激活焓。过氧亚硝酸盐与其他化合物如二甲基亚砜和脱氧核糖在单分子反应中反应，过氧亚硝酸盐的活化是限速的。理论上，活化可能包括(1)异裂解为OH-和NO2+ （δ (rnx) g度' = 13 kcal/mol， pH为7）或(2)均裂解为。OH和。NO2 (δ (rxn) g度= 21 kcal/mol)，这些过程也可能参与到硝酸盐的异构化过程中。然而，热力学和动力学的考虑表明，这两种方法都是不可行的，尽管与金属离子结合可能会降低与异解相关的大活化能。与ONOOH向HONO2异构化过渡态密切相关的中间体可能是ONOOH介导的羟基自由基样氧化的强氧化中间体。因此，过氧亚硝酸盐至少通过两种不同的机制与不同的化合物反应，而羟基自由基都不参与其中。
Peroxynitrite [oxoperoxonitrate(1-), ONOO-] may be formed in vivo from superoxide and nitric oxide. The anion is stable, but the acid (pK(a) = 6.8) decays to nitrate with a rate of 1.3 s-1 at 25-degrees-C. The experimental activation parameters of this process are DELTAH(double dagger) = +18 +/-1 kcal/mol, DELTAS(double dagger) = +3 +/- 2 cal/(mol.K), and DELTAG(double dagger) = +17 +/- 1 kcal/mol. Peroxynitrite (or its protonated form) oxidizes some compounds such as thiols and thioethers in a bimolecular reaction. The reactions with glutathione and cysteine have activation enthalpies of 10.9 and 9.7 kcal/mol, respectively, which are lower than that of the isomerization reaction. Peroxynitrite reacts with other compounds such as dimethyl sulfoxide and deoxyribose in a unimolecular reaction for which the activation of peroxynitrite is rate-limiting. In theory, activation could involve (1) heterolysis to OH- and NO2+ (DELTA(rnx)G-degrees' = 13 kcal/mol at pH 7) or (2) homolysis to .OH and .NO2 (DELTA(rxn)G-degrees = 21 kcal/mol), and these processes also could be involved in the isomerization to nitrate. However, thermodynamic and kinetic considerations indicate that neither process is feasible, although binding to metal ions may reduce the large activation energy associated with heterolysis. An intermediate closely related to the transition state for isomerization of ONOOH to HONO2 may be the strongly oxidizing intermediate responsible for hydroxyl radical-like oxidations mediated by ONOOH. Thus, peroxynitrite reacts with different compounds by at least two distinct mechanisms, and the hydroxyl radical is not involved in either.