Beckerson Penny, Svistunenko Dimitri, Reeder Brandon
School of Biological Sciences, University of Essex, Colchester, Essex, CO4 3SQ, UK.
F1000Res. 2015 Apr 7;4:87. doi: 10.12688/f1000research.5971.1. eCollection 2015.
The reaction of hydrogen peroxide with ferric human cytoglobin and a number of distal histidine variants were studied. The peroxidase activity of the monomeric wildtype protein with an internal disulfide bond, likely to be the form of the protein in vivo, exhibits a high peroxidase-like activity above that of other globins such as myoglobin. Furthermore, the peroxidatic activity of wildtype cytoglobin shows increased resistance to radical-based degradation compared to myoglobin. The ferryl form of wildtype cytoglobin is unstable, but is able to readily oxidize substrates such as guaiacol. In contrast distal histidine mutants of cytoglobin (H81Y and H81V) show very low peroxidase activity but enhanced radical-induced degradation. Therefore, the weakly bound distal histidine appears to modulate ferryl stability and limit haem degradation. These data are consistent with a role of a peroxidase activity of cytoglobin in cell stress response mechanisms.
研究了过氧化氢与人类铁细胞血红蛋白以及一些远端组氨酸变体的反应。具有内部二硫键的单体野生型蛋白的过氧化物酶活性，可能是该蛋白在体内的存在形式，其过氧化物酶样活性高于其他球蛋白如肌红蛋白。此外，与肌红蛋白相比，野生型细胞血红蛋白的过氧化活性对基于自由基的降解具有更高的抗性。野生型细胞血红蛋白的高铁形式不稳定，但能够轻易氧化诸如愈创木酚等底物。相比之下，细胞血红蛋白的远端组氨酸突变体（H81Y和H81V）显示出非常低的过氧化物酶活性，但自由基诱导的降解增强。因此，弱结合的远端组氨酸似乎调节高铁稳定性并限制血红素降解。这些数据与细胞血红蛋白的过氧化物酶活性在细胞应激反应机制中的作用一致。
