Effects of oxyradicals on oxymyoglobin. Deoxygenation, haem removal and iron release.
Effects of oxyradicals on oxymyoglobin. Deoxygenation, haem removal and iron release.
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氧自由基对氧合肌红蛋白的影响。
DOI：
10.1042/bj2630731
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Das,DK
中科院分区：
文献类型：
--
作者：
Prasad,MR;Engelman,RM;Jones,RM;Das,DK
我们研究了 O2 衍生的自由基对氧合肌红蛋白（参与 O2 储存和运输的心肌细胞内蛋白）的影响。黄嘌呤/黄嘌呤氧化酶系统产生的氧自由基降低了氧合肌红蛋白的浓度。根据 581 nm 和 415 nm 处吸光度峰的降低，估计氧合肌红蛋白减少 10 nmol 中，其中 5 nmol 似乎被氧化为铁肌红蛋白（脱氧），而血红素则从另外 5 nmol 血红素蛋白中去除。这些过程可被单独的过氧化氢酶和超氧化物歧化酶与过氧化氢酶组合抑制，但不能被单独的超氧化物歧化酶或去铁胺抑制。这些结果表明，H2O2 中存在 OH。和O2.-，只有H2O2引起血红素的去除和氧合肌红蛋白的氧化。此外，氧自由基还从氧合肌红蛋白中释放出 3 µM 游离铁，这比氧合肌红蛋白损失的 15 nmol 至少少 5 倍。氧合肌红蛋白的损失也在游离铁的释放之前发生。这些结果表明氧合肌红蛋白氧化和血红素去除发生在游离铁去除之前。因此，肌红蛋白似乎对自由基攻击高度敏感，这可能代表自由基介导的细胞损伤的另一种机制。
We have examined the effects of O2-derived free radicals on oxymyoglobin, the myocardial intracellular protein involved in the storage and transport of O2. The oxyradicals generated by the xanthine/xanthine oxidase system decreased the concentration of oxymyoglobin. Based on the decreases in absorbance peaks at 581 nm and 415 nm it is estimated that out of a 10 nmol decrease in oxymyoglobin, 5 nmol appears to be oxidized to ferrimyoglobin (deoxygenation), while haem was removed from the other 5 nmol of haem protein. These processes were inhibited by both catalase alone and superoxide dismutase in combination with catalase, but not by either superoxide dismutase alone or deferoxamine. These results suggest that among H2O2, OH. and O2.-, only H2O2 causes the removal of haem and the oxidation of oxymyoglobin. Furthermore, the oxyradicals also released 3 microM free iron from oxymyoglobin, which is at least 5-fold less than the 15 nmol loss of oxymyoglobin. The loss of oxymyoglobin also preceded the release of free iron. These results indicate that oxymyoglobin oxidation and haem removal occur before the removal of free iron. Thus myoglobin appears to be highly susceptible to free radical attack, and this may represent yet another mechanism of free radical-mediated cellular injury.