Nitrosothiol formation catalyzed by ceruloplasmin -: Implication for cytoprotective mechanism in vivo
Nitrosothiol formation catalyzed by ceruloplasmin -: Implication for cytoprotective mechanism in vivo
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DOI：
10.1074/jbc.274.38.27069
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发表时间：
1999-09-17
影响因子：
4.8
通讯作者：
Maeda, H
中科院分区：
文献类型：
--
作者：
Inoue, K;Akaike, T;Maeda, H
铜蓝蛋白（Ceruloplasmin， CP）是一种主要的含多铜血浆蛋白，不仅通过其氧化铁酶活性参与铁代谢，而且还具有抗氧化剂的功能。然而，CP的生理底物尚未完全确定，CP的作用也尚未完全了解。从生成亚硝基硫醇（RS-NO）的角度研究了一氧化氮（NO）与CP的反应。首先，用生理相关浓度的NO和各种硫醇化合物（RSH）如谷胱甘肽（GSH）检测重金属或cp催化的RS-NO的形成。在各种重金属离子和含铜酶及蛋白质中，只有铜离子（Cu2+）和CP表现出较强的RS-NO （s -亚硝基谷胱甘肽）生成活性。此外，外源添加CP对培养中表达诱导NO合成酶的RAW264细胞具有明显的rs -NO形成催化活性，但铜离子则没有这种情况。同样，HepG2细胞内源性产生的CP在细胞培养中显示出强大的rs - no形成活性。一氧化氮的单电子氧化似乎是有效的，通过电子从1型铜转移到CP中的2型和3型铜簇，产生RS-NO。除RS-NO外，s -亚硝基谷胱甘肽尤其对铁超载引起的氧化应激具有神经保护作用。因此，我们认为CP在RS-NO的形成中起着重要的催化作用，这可能有助于其在哺乳动物生物系统中有效的抗氧化和细胞保护作用。
Ceruloplasmin (CP) is a major multicopper-containing plasma protein that is not only involved in iron metabolism through its ferroxidase activity but also functions as an antioxidant. However, physiological substrates for CP have not been fully identified nor has the role of CP been fully understood. The reaction of nitric oxide (NO) with CP was investigated in view of nitrosothiol (RS-NO) formation. First, formation of heavy metal- or CP-catalyzed RS-NO was examined with physiologically relevant concentrations of NO and various thiol compounds (RSH) such as glutathione (GSH). Among the various heavy metal ions and copper-containing enzymes and proteins examined, only copper ion (Cu2+) and CP showed potent RS-NO (S-nitrosoglutathione)-producing activity. Also, RS-NO-forming catalytic activity was evident for CP added exogenously to RAW264 cells expressing inducible NO synthase in culture, but this was not the case for copper ion. Similarly, CP produced endogenously by HepG2 cells showed potent RS-NO-forming activity in the cell culture. One-electron oxidation of NO appears to be operative for RS-NO production via electron transfer from type 1 copper to a cluster of types 2 and 3 copper in CP. Neurological disorders are associated with aceruloplasminemia; besides RS-NO, S-nitrosoglutathione particularly has been shown to have neuroprotective effect against oxidative stress induced by iron overload. Thus, we suggest that CP plays an important catalytic role in RS-NO formation, which may contribute to its potent antioxidant and cytoprotective activities in vivo in mammalian biological systems.