铜锌超氧物歧化酶对几种羟自由基产生系统的影响

EFFECTS OF CuZn-SUPEROXIDE DISMUTASE ON SEVERAL HYDROXYL RADICAL GENERATING SYSTEMS

应用脱氧核糖降解法研究了ＣｕＺｎ－ＳＯＤ对几种·ＯＨ产生系统的作用机理．结果证明：ＳＯＤ对Ｆｅ（３＋）·Ｏ·Ｈ２Ｏ２系统中·ＯＨ的产生有明显的抑制作用，而失活ＳＯＤ或ＢＳＡ对它的抑制作用不大；在Ｆｅ（２＋）·Ｈ２Ｏ２和ＣＵ（２＋）·Ｈ２Ｏ２系统中，ＳＯＤ、失活ＳＯＤ和ＢＡＳ均能抑制·ＯＨ的产生；在Ｆｅ（２＋）·Ｏ系统中，ＳＯＤ对·ＯＨ产生作用不大，而失活ＳＯＤ或ＢＳＡ对它有明显的抑制作用．由此推测ＳＯＤ对·ＯＨ形成可能有三方面的影响：１．对Ｏ的清除作用，阻断Ｈａｂｅｒ－Ｗｅｉｓｓ反应；２．对金属离子的络合作用，降低·ＯＨ的产额；３．促进Ｈ２Ｏ２的积累，加快Ｆｅｎｔｏｎ反应．

The effects of CuZn-superoxide dismutase (SOD) on several hydroxyl radical generating systems were studied by using deoxyribose which reacted with hydroxyl radical to release thiobarbituric acid-reactivity compounds. When hydroxyl radical was formed in the Fe3+·O· H2O2 system, its formation was effectively inhibited by SOD, and just slightly inhibited by inactive SOD or bovine serum albudrin (BSA). In Fe(2+)· H2O2 or Cu(2+)· H2O2 system,the hydroxyl radical production was significantly inhibited by BSA. inactive SOD, or SOD which had similar effect to that of inactive SOD. The hydroxyl radical generation from Fe(2+)·O system could be effectively suppressed by inactive SOD or BSA, but not by the 'active' SOD which had little effect on hydroxyl radical generation from this system. It is suggested that SOD could affect the hydroxyl radical formation through the following pathways: 1. scavenging superoxide to inhibit Haber-Weiss reaction, 2. chelating metal ions to decrease hydroxyl radical formation; 3. accelerating H2O2 accumulation to enhance hydroxyl radical formation from Fenton reaction.