Sensitivity of protein sulfhydryl repair enzymes to oxidative stress.
Sensitivity of protein sulfhydryl repair enzymes to oxidative stress.
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DOI：
10.1016/s0891-5849(97)00009-9
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发表时间：
1997
影响因子：
7.4
通讯作者：
D. W. Starke;Yuegang Chen;Chandra P Bapna;E. Lesnefsky;J. Mieyal
中科院分区：
文献类型：
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作者：
D. W. Starke;Yuegang Chen;Chandra P Bapna;E. Lesnefsky;J. Mieyal
根据已证实的活性，硫醇-二硫代氧化还原酶(TDOR)酶系统[硫醇转移酶(谷氧还蛋白)和GSSG还原酶；硫氧还蛋白和硫氧还蛋白还原酶]有望为氧化应激下的硫代蛋白的保护和修复提供主要的细胞机制。由于所有四种酶都有活性部位二硫醇部分，它们本身可能容易受到氧化损伤。因此，使用羟基自由基生成系统(络合亚铁和过氧化氢相结合)来记录每个酶对体外氧化应激的相对敏感性。在特定浓度的酶和氧化剂体系下，所有酶几乎完全失活，但观察到不同的敏感性模式。在大致生理浓度下，硫氧还蛋白和硫醇转移酶对1 mM Fe2+-ADP和1 mM H_2O_2有较大的失活作用，而硫氧还蛋白还原酶和硫氧还蛋白还原酶的敏感性较低：10μM硫氧还蛋白(88%失活)，1μM硫醇转移酶(72%)，2μM硫氧还蛋白还原酶(5%)和0.1μM GSSG还原酶(17%)。当氧化剂体系的浓度从1 mM逐步降低到1μM以模拟可能与原位氧化组织损伤相关的条件时，硫氧还蛋白的失活成比例地减少，而硫醇转移酶仍然更敏感。正如预期的那样，GSH和其他自由基清除剂保护硫醇转移酶不被Fe(ADP)-H_2O_2灭活。为了测试TDOR酶在类似生理环境下对氧化应激的敏感性，对离体灌流的兔心进行了30min的缺血和30min的再灌流。GSH/GSSG比值和总脱硫酶活性(硫醇转移酶和硫氧还蛋白系统)与对照心脏相比保持不变，表明在中度原位氧化应激过程中，整体氧化还原状态和巯基修复活性保持不变。
According to their demonstrated activities, the thiol-disulfide oxidoreductase (TDOR) enzyme systems [thioltransferase (glutaredoxin) and GSSG reductase; and thioredoxin and thioredoxin reductase] are expected to provide the primary cellular mechanism for protection and repair of sulfhydryl proteins under oxidative stress. Since all four enzymes have active site dithiol moieties, they may be vulnerable to oxidative damage themselves. Therefore, an hydroxyl radical generating system (chelated ferrous iron in combination with hydrogen peroxide) was used to document the relative sensitivity of each of the enzymes to oxidative stress in vitro. At particular concentrations of enzymes and oxidant system, all of the enzymes were deactivated nearly completely, but different patterns of susceptibility were observed. At the approximate physiological concentration of each enzyme thioredoxin and thioltransferase were largely deactivated with 1 mM Fe2+-ADP, 1 mM H2O2; whereas thioredoxin reductase and GSSG reductase were much less sensitive: 10 μM thioredoxin (88% deactivated), 1 μM thioltransferase (72%), 2 μM thioredoxin reductase (5%), and 0.1 μM GSSG reductase (17%). As the concentration of the oxidant system was decreased stepwise from 1 mM to 1 μM to mimic conditions that may be associated with oxidative tissue injury in situ, deactivation of thioredoxin was decreased proportionately, whereas thioltransferase remained much more susceptible. As expected GSH and other radical scavengers protected thioltransferase from deactivation by Fe(ADP)-H2O2. To test the susceptibility of the TDOR enzymes to oxidative stress in a physiological-like setting, isolated perfused rabbit hearts were subjected to 30 min ischemia and 30 min reperfusion. The GSH/GSSG ratio and total dethiolase activity (thioltransferase and thioredoxin systems) remained unchanged relative to control hearts, indicating that overall redox status and sulfhydryl repair activity are maintained during moderate oxidative stress in situ.