Sulfhydryl oxidase from egg white - A facile catalyst for disulfide bond formation in proteins and peptides
Sulfhydryl oxidase from egg white - A facile catalyst for disulfide bond formation in proteins and peptides
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DOI：
10.1074/jbc.274.32.22147
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发表时间：
1999-08-06
影响因子：
4.8
通讯作者：
Thorpe, C
中科院分区：
文献类型：
--
作者：
Hoober, KL;Sheasley, SL;Thorpe, C
金属蛋白和黄素连接的巯基氧化酶都催化硫醇氧化成二硫化物，并将氧还原成过氧化氢。尽管早期提出了在蛋白质二硫键形成中的作用，但这些酶受到的关注相对较少。鸡卵白色巯基氧化酶利用内部氧化还原活性胱氨酸桥和FAD部分氧化一系列小分子量硫醇，如谷胱甘肽、半胱氨酸和二硫苏糖醇。此处显示该氧化酶对一系列还原肽和蛋白质，包括胰岛素A和B链、溶菌酶、卵清蛋白、核黄素结合蛋白和RNA酶表现出高催化活性，催化效率比还原型谷胱甘肽高100倍，与谷胱甘肽的20 mM相比，典型的K-m值为约110-330 μ M/蛋白硫醇。当半胱氨酸残基被巯基氧化酶快速氧化时，RNA酶活性没有显著恢复，但当蛋白质二硫键异构酶也存在时，活性有效恢复。巯基氧化酶也可直接氧化还原型蛋白质二硫键异构酶。这些数据表明，巯基氧化酶和蛋白质二硫键异构酶可以在体外合作的天然二硫键配对的产生和重排。氧化酶在体内蛋白质分泌途径中的可能作用进行了讨论。
Both metalloprotein and flavin-linked sulfhydryl oxidases catalyze the oxidation of thiols to disulfides with the reduction of oxygen to hydrogen peroxide, Despite earlier suggestions for a role in protein disulfide bond formation, these enzymes have received comparatively little general attention. Chicken egg white sulfhydryl oxidase utilizes an internal redox-active cystine bridge and a FAD moiety in the oxidation of a range of small molecular weight thiols such as glutathione, cysteine, and dithiothreitol, The oxidase is shown here to exhibit a high catalytic activity toward a range of reduced peptides and proteins including insulin A and B chains, lysozyme, ovalbumin, riboflavin-binding protein, and RNase, Catalytic efficiencies are up to 100-fold higher than for reduced glutathione, with typical K-m values of about 110-330 mu M/protein thiol, compared with 20 mM for glutathione. RNase activity is not significantly recovered when the cysteine residues are rapidly oxidized by sulfhydryl oxidase, but activity is efficiently restored when protein disulfide isomerase is also present. Sulfhydryl oxidase can also oxidize reduced protein disulfide isomerase directly. These data show that sulfhydryl oxidase and protein disulfide isomerase can cooperate in vitro in the generation and rearrangement of native disulfide pairings. A possible role for the oxidase in the protein secretory pathway in vivo is discussed.