METHIONINE SULFOXIDE REDUCTASE

蛋白质暴露在氧气中，尤其是暴露在还原氧中 化合物，如过氧化氢和羟基自由基，允许 蛋白质分子上敏感部位的氧化。对敏感的人 网站，蛋氨酸的硫磺特别容易受到攻击。一个 蛋氨酸亚麻酸还原酶可以逆转这种氧化和 它已被证明在氧化损伤的持续修复中起着重要作用。 受损的蛋白质。对这种酶的分析表明，有一种 增加的大鼠肝脏中稳定的，如果不是戏剧性的活动丧失 年龄，在24个月时下降到2个月时的80%。 这些发现表明，衰老的影响之一是减少。 修复受损酶的能力。不同树种植物提取物的研究概况 脏器显示，酶活性在大鼠体内广泛分布 肾脏的活性最强。这样的分布 支持酶在维持生命的过程中起重要作用的假说 在牢房里。肾脏的高水平活动可能代表着 该酶在回收氧化蛋氨酸中的应用 节省了对替代来源的营养需求。蛋氨酸 从大肠埃希氏菌中分离纯化了亚砜还原酶。鉴于 在生长过程中，大肠杆菌的培养物中有低水平的活性， 在稳定期，电离层浓度急剧上升。

Exposure of proteins to oxygen and, especially, to reduced oxygen compounds, such as hydrogen peroxide and hydroxyl radical, permits the oxidation of sensitive sites on the protein molecules. Of the sensitive sites, the sulfur of methionine is particularly subject to attack. An enzyme, methionine sulfoxide reductase, can reverse this oxidation and it has been shown to be a player in the continuing repair of oxidatively damaged proteins. Assays for this enzyme have shown that there is a steady, if undramatic, loss in activity in livers of rats of increasing age, falling at 24 months to values 80 percent of those at 2 months. These findings suggest that one of the effects of aging is decreased ability to repair damaged enzymes. Surveys of extracts of different organs show that the enzyme activity is widely distributed in the rat with the greatest activity found in the kidney. Such distribution supports the hypothesis that the enzyme is important in the maintenance of the cell. The high level of activity in the kidney may represent the utility of the enzyme in reclaiming oxidized methionine and thereby sparing the nutritional demands for replacement sources. Methionine sulfoxide reductase has been purified from Escherichia coli. Whereas there is a low level of activity in cultures of E. coli during growth, the levels rise dramatically in stationary phase.