Bozzi A, Mavelli I, Finazzi A, Strom R, Wolf A M, Mondovi B, Rotilio G
Mol Cell Biochem. 1976 Jan 31;10(1):11-6. doi: 10.1007/BF01731676.
The enzymatic destruction of oxidizing products produced during metabolic reduction of oxygen in the cell (such as singlet oxygen, H2O2 and OH radical) involves the concerted action of superoxide dismutase-which removes O-2 and yields H2O2-and H2O2 removing enzymes such as catalase and glutathione peroxidase. A difference in distribution or ratio of these enzymes in various tissues may result in a different reactivity of oxygen radicals. It was found that in red blood cells superoxide dismutase and catalase are extracted in the same fraction as hemoglobin, while glutathione peroxidase appears to be "loosely" bound to the cellular structure. This suggests that in red blood cells catalase acts in series with superoxide dismutase against bursts of oxygen radicals formed from oxyhemoglobin, while glutathione & peroxidase may protect the cell membrane against low concentrations of H2O2. On the other hand, catalase activity is absent in various types of ascites tumor cells, while glutathione peroxidase and superoxide dismutase are found in the cytoplasm. However, the peroxidase/dismutase ratio is lower than in liver cells, and this may provide an explanation for the higher susceptibility of tumor cells to treatments likely to involve oxygen radicals.
细胞内氧代谢还原过程中产生的氧化产物（如单线态氧、过氧化氢和羟基自由基）的酶促破坏涉及超氧化物歧化酶（其去除超氧阴离子并产生过氧化氢）与过氧化氢去除酶（如过氧化氢酶和谷胱甘肽过氧化物酶）的协同作用。这些酶在不同组织中的分布或比例差异可能导致氧自由基的反应性不同。研究发现，在红细胞中，超氧化物歧化酶和过氧化氢酶与血红蛋白在同一组分中被提取出来，而谷胱甘肽过氧化物酶似乎“松散地”结合于细胞结构。这表明在红细胞中，过氧化氢酶与超氧化物歧化酶协同作用，对抗由氧合血红蛋白形成的氧自由基爆发，而谷胱甘肽过氧化物酶可能保护细胞膜免受低浓度过氧化氢的损伤。另一方面，各种类型的腹水肿瘤细胞中不存在过氧化氢酶活性，而谷胱甘肽过氧化物酶和超氧化物歧化酶存在于细胞质中。然而，过氧化物酶/歧化酶的比例低于肝细胞，这可能解释了肿瘤细胞对可能涉及氧自由基的治疗更敏感的原因。
