Radi R, Sims S, Cassina A, Turrens J F
Departamento de Bioquímica, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay.
Free Radic Biol Med. 1993 Dec;15(6):653-9. doi: 10.1016/0891-5849(93)90169-u.
A recent report (Radi et al., J. Biol. Chem. 266:22028-22034, 1991) showed that rat heart mitochondria contain catalase. The protective role of mitochondrial catalase was tested by exposing heart or kidney mitochondria and mitoplasts to two oxidants (H2O2) or tert-butyl hydroperoxide, t-BOOH), estimating lipid peroxidation (as thiobarbituric acid-reactive substances, TBARS) and overall oxidative stress (as chemiluminescence). Additional controls included heart and kidney preparations from aminotriazole-treated (catalase-depleted) rats. Both oxidants increased TBARS in catalase-free preparations to similar extents over their respective controls (between 200 to 350%). In catalase-containing preparations, H2O2 lipid peroxidation increased by only 40 to 96% over controls. Similar qualitative results were obtained when measuring chemiluminescence. The catalytic role of cytochrome c in mitochondrial lipid peroxidation was investigated by exposing either control or cytochrome-c-depleted kidney mitoplasts (catalase free) to either H2O2 or t-BOOH. Hydrogen-peroxide-dependent mitochondrial lipid peroxidation varied with cytochrome c concentration, remaining close to controls when cytochrome c concentration decreased by 66%, even though there was no catalase present. Tert-butyl hydroperoxide-dependent lipid peroxidation was less affected by cytochrome c remaining 2.3-fold above controls under the same conditions, suggesting that organic peroxides are more likely to remain in the less polar membrane environment being decomposed by heme or nonheme iron imbedded in the inner mitochondrial membrane. Chemiluminescence was less affected by cytochrome c depletion. Comparing control and cytochrome-c-deficient mitochondria, chemiluminescence was 1.7-fold and 2.8-fold higher when control preparations were challenged with t-BOOH or H2O2, respectively.
最近的一份报告（Radi等人，《生物化学杂志》266:22028 - 22034，1991年）表明，大鼠心脏线粒体含有过氧化氢酶。通过将心脏或肾脏线粒体及线粒体膜泡暴露于两种氧化剂（过氧化氢或叔丁基过氧化氢，t - BOOH），测定脂质过氧化（以硫代巴比妥酸反应性物质，TBARS表示）和整体氧化应激（以化学发光表示），来测试线粒体过氧化氢酶的保护作用。额外的对照包括来自经氨基三唑处理（过氧化氢酶耗尽）大鼠的心脏和肾脏制剂。两种氧化剂在无过氧化氢酶的制剂中使TBARS相对于各自的对照增加到相似程度（在200%至350%之间）。在含有过氧化氢酶的制剂中，过氧化氢导致的脂质过氧化仅比对照增加40%至96%。在测量化学发光时也获得了类似的定性结果。通过将对照或细胞色素c缺失的肾脏线粒体膜泡（无过氧化氢酶）暴露于过氧化氢或叔丁基过氧化氢，研究了细胞色素c在线粒体脂质过氧化中的催化作用。过氧化氢依赖性线粒体脂质过氧化随细胞色素c浓度而变化，当细胞色素c浓度降低66%时，即使不存在过氧化氢酶，其仍接近对照水平。叔丁基过氧化氢依赖性脂质过氧化受细胞色素c的影响较小，在相同条件下比对照高2.3倍，这表明有机过氧化物更有可能留在极性较小的膜环境中，被嵌入线粒体内膜的血红素或非血红素铁分解。化学发光受细胞色素c缺失的影响较小。比较对照和细胞色素c缺陷的线粒体，当对照制剂用叔丁基过氧化氢或过氧化氢攻击时，化学发光分别高1.7倍和2.8倍。
