An X-ray crystallographic study of the binding sites of the azide inhibitor and organic substrates to ceruloplasmin, a multi-copper oxidase in the plasma
An X-ray crystallographic study of the binding sites of the azide inhibitor and organic substrates to ceruloplasmin, a multi-copper oxidase in the plasma
复制标题
叠氮化物抑制剂和有机底物与血浆中的多铜氧化酶铜蓝蛋白结合位点的 X 射线晶体学研究
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
P. Lindley
中科院分区：
文献类型：
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作者：
V. Zaitsev;I. Zaitseva;M. Papiz;P. Lindley
铜蓝蛋白是一种多铜氧化酶，它含有血浆中的大部分铜。它是一种急性期反应物，在成人血浆中比正常浓度300 μg/ml增加2 - 3倍。然而，血浆铜蓝蛋白的确切生理作用一直是激烈辩论的主题，并且该酶可能具有多功能作用，包括铁氧化酶活性和生物胺的氧化。人类酶的三维X射线结构在1996年被阐明，并表明该分子由六个以三角形阵列排列的铜氧还蛋白型结构域组成。每个分子有六个完整的铜原子（结构域2，4和6中的单核位点和结构域1和6之间的三核位点）和两个不稳定的位点，约占50%。对金属阳离子结合酶的进一步结构研究表明了铁氧化酶活性的推定机制。在本文中，我们报告了中等分辨率的X射线研究（3.0-3.5 μ m），定位抑制剂（叠氮化物）和各种底物[芳香族二胺，生物胺和（+）-麦角酸二乙基酰胺，LSD]的结合位点。叠氮化物部分的结合位点在拓扑学上等同于抗坏血酸氧化酶报道的位点之一。然而，胺底物有两个不同的结合位点：芳香族二胺结合在远离单核铜位点的结构域4的底部，而以血清素、肾上腺素和多巴为代表的生物胺系列结合在结构域6中的阳离子所利用的附近，并靠近单核铜。这些结合位点进行了讨论，在可能的氧化机制。还报道了LSD的结合位点。
Abstract Ceruloplasmin is a multi-copper oxidase, which contains most of the copper present in the plasma. It is an acute-phase reactant that exhibits a two- to three-fold increase over the normal concentration of 300 μg/ml in adult plasma. However, the precise physiological role(s) of ceruloplasmin has been the subject of intensive debate and it is likely that the enzyme has a multi-functional role, including iron oxidase activity and the oxidation of biogenic amines. The three-dimensional X-ray structure of the human enzyme was elucidated in 1996 and showed that the molecule was composed of six cupredoxin-type domains arranged in a triangular array. There are six integral copper atoms per molecule (mononuclear sites in domains 2, 4 and 6 and a trinuclear site between domains 1 and 6) and two labile sites with roughly 50% occupancy. Further structural studies on the binding of metal cations by the enzyme indicated a putative mechanism for ferroxidase activity. In this paper we report medium-resolution X-ray studies (3.0–3.5 Å) which locate the binding sites for an inhibitor (azide) and various substrates [aromatic diamines, biogenic amines and (+)-lysergic acid diethylamide, LSD]. The binding site of the azide moiety is topologically equivalent to one of the sites reported for ascorbate oxidase. However, there are two distinct binding sites for amine substrates: aromatic diamines bind on the bottom of domain 4 remote from the mononuclear copper site, whereas the biogenic amine series typified by serotonin, epinephrine and dopa bind in close vicinity to that utilised by cations in domain 6 and close to the mononuclear copper. These binding sites are discussed in terms of possible oxidative mechanisms. The binding site for LSD is also reported.