Baron Caroline P, Møller Jens K S, Skibsted Leif H, Andersen Henrik J
Department of Seafood Research, Danish Institute for Fisheries Research, Technical University of Denmark, Kgs Lyngby, Denmark.
Free Radic Res. 2007 Aug;41(8):892-902. doi: 10.1080/10715760701416475.
Nitrosylmyoglobin (MbFe(II)NO), which is believed to have a protective role during ischemia and reperfusion injury, was oxidized by tert-butyl hydroperoxide (t-BuOOH), and by hydrogen peroxide (H(2)O(2)) to the nitrite anion and metmyoglobin (MbFe(III)). Further characterization of the reaction of MbFe(II)NO with excess of t-BuOOH was investigated with respect to reaction stoichiometry, temperature and pH dependence. It was found that the reaction between MbFe(II)NO with excess of t-BuOOH followed a simple stoichiometry and had moderate pH and temperature dependence with the activation parameters DeltaH(double dagger) = 57.4 +/- 1.4 kJ mol(- 1) and DeltaS(double dagger) = - 112.0 +/- 5.1 J mol(- 1) K(- 1), which is consistent with an associative reaction mechanism. Moreover, t-BuOOH-induced oxidation of MbFe(II)NO did not result in any detectable formation of the hypervalent myoglobin (Mb) species, i.e. perferrylmyoglobin, (( radical)MbFe(IV) = O) or ferrylmyoglobin (MbFe(IV) = O), and hereby differed from H(2)O(2)-induced oxidation of MbFe(II)NO, which results in the formation of MbFe(IV) = O. Based on the obtained results and on published data, different mechanisms for the reaction of the MbFe(II)NO with t-BuOOH and H(2)O(2) are proposed.
亚硝酰肌红蛋白（MbFe(II)NO）被认为在缺血再灌注损伤过程中具有保护作用，它被叔丁基过氧化氢（t-BuOOH）和过氧化氢（H₂O₂）氧化为亚硝酸根阴离子和高铁肌红蛋白（MbFe(III)）。针对反应化学计量、温度和pH依赖性，对MbFe(II)NO与过量t-BuOOH的反应进行了进一步表征。发现MbFe(II)NO与过量t-BuOOH之间的反应遵循简单的化学计量关系，并且对pH和温度有适度的依赖性，活化参数ΔH‡ = 57.4 ± 1.4 kJ mol⁻¹和ΔS‡ = -112.0 ± 5.1 J mol⁻¹ K⁻¹，这与缔合反应机理一致。此外，t-BuOOH诱导的MbFe(II)NO氧化未导致任何可检测到的高价肌红蛋白（Mb）物种的形成，即过氧高铁肌红蛋白（(•)MbFe(IV)=O）或高铁肌红蛋白（MbFe(IV)=O），因此与H₂O₂诱导的MbFe(II)NO氧化不同，后者会导致MbFe(IV)=O的形成。基于所得结果和已发表的数据，提出了MbFe(II)NO与t-BuOOH和H₂O₂反应的不同机制。
