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作 者 ：韦金池, 杨海灵

期 刊 ：植物科学学报 2013年 31卷 1期 页码：64-72

关键词：谷胱甘肽过氧化物酶；水稻；克隆；蛋白结构；酶活性分析；

Keywords:Glutathione peroxidase, Oryza sativa, Cloning, Protein structure, Enzyme activity,

摘 要 ：植物谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)是清除体内活性氧的一种关键酶,在植物抗逆反应中发挥重要作用.本研究从水稻中克隆到2个GPX基因,分别为OsGPX3和OsGPX4.OsGPX3和OsGPX4分别编码238和234个氨基酸组成的蛋白质,预测分子量分别是25.84 kD和25.07 kD.两个基因都包含5个内含子,但是两个基因所对应的内含子长度具有较大变异.组织表达谱分析发现这2个基因在根、茎、叶和叶鞘中均表达,是组成型表达基因.在大肠杆菌中表达并纯化了这2个基因的重组蛋白,酶活性分析显示OsGPX3和OsGPX4蛋白对底物H₂O₂、tBOOH和COOH具有较高活性,但是OsGPX3对3种底物的活性均高于OsGPX4,蛋白质酶活性的差异预示着这2个基因可能存在功能上的分化.

Abstract:Plant glutathione peroxidases (GPX) are a group of enzymes that regulate levels of reactive oxygen species in cells and tissues,and protect them against oxidative damage.In this study,two GPX genes (OsGPX3 and OsGPX4) were cloned from Oryza sativa.The OsGPX3 and OsGPX4 genes encoded two proteins of 238 and 234 amino acid residues,with calculated molecular masses of 25.84 kDa and 25.07 kDa,respectively.Genomic sequence analysis showed OsGPX3 and OsGPX4 contained five introns.Reverse transcription PCR revealed that OsGPX3 and OsGPX4 were constitutive expression genes in O.sativa.The OsGPX3 and OsGPX4 proteins were overexpressed in E.coli,and were purified by Ni-affinity chromatography.The OsGPX3 and OsGPX4 proteins showed enzymatic activities towards substrates H₂O₂,tBOOH and COOH.However,OsGPX3 showed higher enzymatic activities to the three substrates than did OsGPX4,suggesting functional divergence between the OsGPX3 and OsGPX4 genes.

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