Hu M L, Tappel A L
Department of Food Science and Technology, University of California, Davis 95616.
Lipids. 1992 Jan;27(1):42-5. doi: 10.1007/BF02537057.
The study investigated the relationship between lipid peroxidation and enzyme inactivation in rat hepatic microsomes and whether prior inactivation of aldehyde dehydrogenase (ALDH) exacerbated inactivation of other enzymes. In microsomes incubated with 2.5 microM iron as ferric sulfate and 50 microM ascorbate, ALDH, glucose-6-phosphatase (G6Pase) and cytochrome P450 (Cyt-P450) levels decreased rapidly and concurrently with increased levels of thiobarbituric acid-reactive substances. Microsomal glutathione S-transferase and nicotinamide adenine dinucleotide phosphate-cytochrome c reductase were little affected during 1 hr of incubation. Addition of reduced glutathione partially protected and N,N'-diphenyl-p-phenylenediamine and butylated hydroxytoluene completely protected microsomes against inactivation of ALDH, G6Pase and Cyt-P450, as well as lipid peroxidation induced by iron and ascorbate. ALDH was more susceptible than G6Pase to inactivation by iron and ascorbate, and was thus an excellent marker for oxidative stress. Inhibition of ALDH by cyanamide injection of rats exacerbated the inactivation of G6Pase in microsomes incubated with 0.1 mM, but not 25 microM 4-hydroxynonenal (4-HN). 4-HN did not stimulate lipid peroxidation. Thus, 4-HN may play a minor role in microsomal enzyme inactivation. In contrast, lipid peroxyl radicals play an important role in microsomal enzyme inactivation, as evidenced by the prevention of both lipid peroxidation and enzyme inactivation by chain-breaking antioxidants.
该研究调查了大鼠肝微粒体中脂质过氧化与酶失活之间的关系，以及醛脱氢酶（ALDH）预先失活是否会加剧其他酶的失活。在用2.5微摩尔硫酸铁形式的铁和50微摩尔抗坏血酸孵育的微粒体中，ALDH、葡萄糖-6-磷酸酶（G6Pase）和细胞色素P450（Cyt-P450）水平迅速下降，同时硫代巴比妥酸反应性物质水平升高。微粒体谷胱甘肽S-转移酶和烟酰胺腺嘌呤二核苷酸磷酸-细胞色素c还原酶在孵育1小时期间受影响较小。添加还原型谷胱甘肽可部分保护微粒体，而N，N'-二苯基对苯二胺和丁基化羟基甲苯可完全保护微粒体免受ALDH、G6Pase和Cyt-P450失活以及铁和抗坏血酸诱导的脂质过氧化的影响。ALDH比G6Pase更容易被铁和抗坏血酸失活，因此是氧化应激的一个极好标志物。通过向大鼠注射氰胺抑制ALDH会加剧在与0.1毫摩尔而非25微摩尔4-羟基壬烯醛（4-HN）孵育的微粒体中G6Pase的失活。4-HN不会刺激脂质过氧化。因此，4-HN在微粒体酶失活中可能起次要作用。相比之下，脂质过氧自由基在微粒体酶失活中起重要作用，这一点可通过链断裂抗氧化剂预防脂质过氧化和酶失活得到证明。
