An activity in rat tissues that modifies nitrotyrosine-containing proteins
An activity in rat tissues that modifies nitrotyrosine-containing proteins
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DOI：
10.1073/pnas.95.20.11584
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发表时间：
1998-09-29
影响因子：
11.1
通讯作者：
Murad, F
中科院分区：
文献类型：
--
作者：
Kamisaki, Y;Wada, K;Murad, F
大鼠脾和肺匀浆可修饰含硝基酪氨酸的牛血清白蛋白，经培养后，含硝基酪氨酸的牛血清白蛋白失去其抗原表位，被一种选择性识别含硝基酪氨酸蛋白的单克隆抗体取代。在蛋白酶抑制剂存在的情况下，硝基酪氨酸表位的丢失发生在蛋白质降解和水解的情况下，这种活性在上清中发现，但在脾脏匀浆的颗粒部分没有发现。该因子热不稳定，对胰蛋白酶处理敏感，并以10 kda的保留率通过膜后保留。活性与时间和蛋白浓度有关。内毒素（细菌脂多糖）处理后，脾脏提取物的活性增加了约2倍，表明其活性是可诱导或可调节的。其他含硝基酪氨酸的蛋白也可作为底物，而组织提取物中游离硝基酪氨酸和一些内源性含硝基酪氨酸的蛋白是较差的底物。虽然该反应的产物和可能的辅助因子尚未确定，但这种活性可能是一种“硝基酪氨酸脱硝酶”，它可以逆转蛋白质的硝化作用，从而降低过氧亚硝酸盐的毒性。在大鼠肝脏或肾脏的匀浆中没有观察到这种活性，这表明脱硝酶的明显活性也可能存在一些组织特异性。
Homogenates from rat spleen and lung could modify nitrotyrosine-containing BSA, With incubation, nitrotyrosine-containing BSA lost its epitope to a monoclonal antibody that selectively recognized nitrotyrosine-containing proteins. In the presence of protease inhibitors, the loss of the nitrotyrosine epitope occurred without protein degradation and hydrolysis, This activity was found in supernatant but not particulate fractions of spleen homogenates. The factor was heat labile, was sensitive to trypsin treatment, and was retained after passage through a membrane with a 10-kDa retention. The activity was time- and protein-concentration dependent. The activity increased about 2-fold in spleen extracts with endotoxin (bacterial lipopolysaccharide) treatment of animals, suggesting that the activity is inducible or regulatable. Other nitrotyrosine-containing proteins also served as substrates, while free nitrotyrosine and some endogenous nitrotyrosine-containing proteins in tissue extracts were poor substrates. Although the product and possible cofactors for this reaction have not yet been identified, this activity may be a "nitrotyrosine denitrase" that reverses protein nitration and, thus, decreases peroxynitrite toxicity. This activity was not observed in homogenates from rat liver or kidney, suggesting that there may also be some tissue specificity for the apparent denitrase activity.