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自由基与生物反应和细胞毒性有关.多数自由基反应涉及分子氧的还原,产生具有高度反应活性的氧基如超氧物阴离子(O_2~-)、游离羟基(OH~-)、过氧化氢(H_2O_2),单线氧(~1O_2).人类红细胞处于高氧环境中,且富含多不饱合脂酸及铁,后者为有效的自由基催化剂.红细胞膜一直处于细胞内外自由基包围中,在红细胞内,氧合血红蛋白不断转变为高铁血红蛋白,此过程伴随超氧物阴离子(O_2~-)的产生;在红细胞外,中性粒细胞,巨噬细胞产生H_2O_2及O_2~-.弥散到细胞外环境并与红细胞接触.由于红细胞处于自由基包围中,故具有抗氧化损害的保护机制,包括:过氧化氢酶,谷胱甘肽过氧化物酶,超氧化物歧化酶,维持还原性谷胱甘肽在适当水平的酶系,清除氧化蛋白的蛋白溶解酶,维生素E和C.若红细胞抗氧化能力降低,则其膜脂质将受到过氧化损害并导致正常红细胞衰老,加速各种溶血性贫血及血红蛋白病红细胞的破坏.
Free radicals are associated with biological reactions and cytotoxicity.Most of the free radical reactions involve the reduction of molecular oxygen to produce highly reactive oxygen species such as oxygen anion (O 2 -), free hydroxyl (OH ~ -), hydrogen peroxide (H 2 O 2), single line oxygen (~ 1 O 2) .Human erythrocytes are in high oxygen environment, and are rich in polyunsaturated fatty acid and iron, the latter is an effective free radical catalyst.RBC membrane has been surrounded by free radicals inside and outside the cell , In the red blood cells, oxygenated hemoglobin continues to change to methemoglobin, this process accompanied by the generation of superoxide anion (O_2 ~ -); in red blood cells, neutrophils, macrophages produce H_2O_2 and O_2 ~ -. Diffusion to Extracellular environment and contact with red blood cells.As the red blood cells are surrounded by free radicals, it has antioxidant protection mechanisms, including: catalase, glutathione peroxidase, superoxide dismutase, maintain the reduction Glutathione is at an appropriate level in enzymes that cleave oxidized proteinase, vitamin E and C. If the erythrocytes are less resistant to oxidation, their membrane lipids will be damaged by peroxides and cause normal red blood cell senescence, accelerating various Hemolytic poor Destruction of red blood cells and hemoglobin disorders.