Girotti A W, Thomas J P, Jordan J E
J Free Radic Biol Med. 1985;1(5-6):395-401. doi: 10.1016/0748-5514(85)90152-7.
New evidence in support of zinc's role as a membrane antioxidant is presented. Human erythrocyte membranes in buffered saline underwent catalase- and superoxide dismutase-inhibitable lipid peroxidation when incubated with xanthine, xanthine oxidase, and Fe(III). Free radical mediated peroxidation was measured in terms of thiobarbituric acid reactivity and iodometric determination of lipid hydroperoxides. Whereas Ca(II) had relatively little effect on lipid peroxidation, Zn(II) strongly inhibited the reaction and suppressed peroxidation-dependent lysis of resealed membranes. Inhibition of lipid peroxidation was essentially complete in the presence of 0.1 mM Zn(II), a concentration equivalent to that of added Fe(III). By contrast, Zn(II) had no effect on rose bengal-photosensitized lipid peroxidation, a predominantly nonradical, singlet oxygen-driven process. Zinc(II) also interfered with xanthine/xanthine oxidase/iron-induced peroxidation of Triton X-100-dispersed membranes, but had no effect if EDTA was present. Trivial reasons for inhibition, for example, inactivation of xanthine oxidase or complex formation with O2-, were ruled out by showing that the rate of reduction of cytochrome c by xanthine/xanthine oxidase is not affected by Zn(II). We speculate that Zn(II) acts by interfering with the redox cycling of iron, possibly by competing with the latter for membrane binding sites.
本文提供了新的证据，支持锌作为膜抗氧化剂的作用。当在缓冲盐溶液中的人红细胞膜与黄嘌呤、黄嘌呤氧化酶和Fe(III)一起孵育时，会发生过氧化氢酶和超氧化物歧化酶可抑制的脂质过氧化。通过硫代巴比妥酸反应性和脂质氢过氧化物的碘量法测定来测量自由基介导的过氧化。虽然Ca(II)对脂质过氧化的影响相对较小，但Zn(II)强烈抑制该反应并抑制重新封闭膜的过氧化依赖性裂解。在存在0.1 mM Zn(II)（与添加的Fe(III)浓度相当）的情况下，脂质过氧化的抑制基本完全。相比之下，Zn(II)对孟加拉玫瑰红光敏脂质过氧化没有影响，这是一个主要由非自由基、单线态氧驱动的过程。Zn(II)也会干扰黄嘌呤/黄嘌呤氧化酶/铁诱导的Triton X-100分散膜的过氧化，但如果存在EDTA则没有影响。通过表明黄嘌呤/黄嘌呤氧化酶对细胞色素c的还原速率不受Zn(II)影响，排除了抑制的一些微不足道的原因，例如黄嘌呤氧化酶失活或与O2-形成复合物。我们推测Zn(II)通过干扰铁的氧化还原循环起作用，可能是通过与后者竞争膜结合位点。
