Kosaka H, Imaizumi K, Tyuma I
Biochim Biophys Acta. 1982 Apr 3;702(2):237-41. doi: 10.1016/0167-4838(82)90508-8.
Oxidation of oxyhemoglobin by nitrite is characterized by the presence of a lag phase followed by the autocatalysis. Just before the autocatalysis begins, an asymmetric ESR signal is detected which is similar to that of the methemoglobin radical generated from methemoglobin and H2O2 in shape, g value (2.005), peak-to-peak width (18 G) and other properties, except the difference in the dependence on temperature. Generation of H2O2 is indicated by the prolongation of the lag phase by the addition of catalase. On the other hand, the oxidation is modified by neither superoxide dismutase nor Nitroblue tetrazolium. The oxidation is prolonged in the presence of KCN. The present results indicate a free-radical mechanism for the oxidation in which the asymmetric radical catalyzes the formation of NO2 from NO2- by a peroxidase action and NO2 oxidizes oxyhemoglobin in the autocatalytic phase.
亚硝酸盐对氧合血红蛋白的氧化作用具有一个滞后阶段，随后是自动催化过程。就在自动催化开始之前，检测到一个不对称的电子自旋共振（ESR）信号，其形状、g值（2.005）、峰-峰值宽度（18 G）以及其他特性与由高铁血红蛋白和过氧化氢产生的高铁血红蛋白自由基相似，只是在对温度的依赖性上有所不同。通过添加过氧化氢酶使滞后阶段延长，这表明有过氧化氢生成。另一方面，超氧化物歧化酶和硝基蓝四唑均不会改变这种氧化作用。在氰化钾存在的情况下，氧化过程会延长。目前的结果表明，氧化过程存在自由基机制，即不对称自由基通过过氧化物酶作用催化从亚硝酸根离子形成二氧化氮，并且二氧化氮在自动催化阶段氧化氧合血红蛋白。
