Nickel-dependent oxidative cross-linking of a protein
Nickel-dependent oxidative cross-linking of a protein
复制标题
DOI：
10.1021/tx960170i
复制
发表时间：
1997-03-01
影响因子：
4.1
通讯作者：
Rokita, SE
中科院分区：
文献类型：
--
作者：
Gill, G;RichterRusli, AA;Rokita, SE
一个模型蛋白，核糖核酸酶A（牛胰腺），检查其能力，以配合镍2+和促进选择性氧化。在存在过酸如单过硫酸盐，HSO 5-，镍诱导单体RNA酶A形成二聚体，三聚体，四聚体，和更高的寡聚体，而不产生多肽骨架的片段化。Co 2+和在较小程度上Cu 2+表现出类似的活性。镍依赖性反应似乎是由于蛋白质和Ni 2+之间的特定关联，允许结合镍的瞬时和原位氧化，产生分子间酪氨酸-酪氨酸交联。先前已显示促进鸟嘌呤氧化的大环镍络合物不能模拟游离金属盐的活性。蛋白质二聚体的氨基酸分析证实了每个多肽预期消耗一个酪氨酸并形成二酪氨酸。过量酪氨酸的存在有效地抑制了蛋白质二聚体的形成，而不是产生核糖核酸酶-酪氨酸交联。相反，高浓度的羟基自由基淬灭剂甘露醇仅部分抑制核糖核酸酶二聚化。多肽介导的镍活化及其随后的反应性模拟了可能导致镍在体内不良反应的过程。
A model protein, ribonuclease A (bovine pancreas), was examined for its ability to coordinate Ni2+ and promote selective oxidation. In the presence of a peracid such as monopersulfate, HSO5-, nickel induced the monomeric RNase A to form dimers, trimers, tetramers, and higher oligomers without producing fragmentation of the polypeptide backbone. Co2+ and to a lesser extent Cu2+ exhibited similar activity. The nickel-dependent reaction appeared to result from a specific association between the protein and Ni2+ that allowed for transient and in situ oxidation of the bound nickel to yield intermolecular tyrosine-tyrosine cross-links. Macrocylic nickel complexes that had previously been shown to promote guanine oxidation were unable to mimic the activity of the free metal salt. Amino acid analysis of the protein dimer confirmed the expected consumption of one tyrosine per polypeptide and formation of dityrosine. The presence of excess tyrosine efficiently inhibited formation of the protein dimer and produced instead a ribonuclease-tyrosine cross-link. In contrast, high concentrations of the hydroxyl radical quenching agent mannitol only partially inhibited ribonuclease dimerization. The polypeptide-mediated activation of nickel and its subsequent reactivity mimic a process that could contribute to the adverse effects of nickel in vivo.