用点突变方法研究海参精氨酸激酶的活性位点

为研究动物能量代谢,用点突变的方法从双亚基海参(Stichopusjaponicus)精氨酸激酶中得到了3个突变体:C274A、R283G和H287A,并通过大肠杆菌E.coli表达。大部分精氨酸激酶都以包涵体的形式存在。经过纯化之后对3种突变体的催化活性和一些结构特征进行了分析。这3种突变体丧失了绝大部分催化活力,特别是突变体C274A,与野生型相比除了活性完全丧失之外,结构却几乎没有变化。这3个残基对海参精氨酸激酶结构或功能的保持有着重要作用,Cys274残基可能是海参精氨酸激酶的活性位点。

Active site of arginine kinase from sea cucumber Stichopus japonicus by site mutagenesis

Three mutations: C~274A, R~283G and H~287A, of sea cucumber Stichopus japonicus dimeric arginine kinase were obtained by site mutagenesis to research the energy metabolism of invertebrate animals. The three mutants were then expressed in E.coli.The bulk of the expressed protein resided in insoluble inclusion bodies. The catalytic activity and structural features of the proteins were analyzed to show that all three mutants lost most of their catalytic activity. The mutant C~274A lost almost all of its catalytic activity, but its structure was almost the same as the wild type. The results show that all three residues play important roles in maintaining either the structural or functional integrity of the arginine kinase. The Cys~274might be the active site of ariginine kinase.