作　　者： ; ; ; ;

机构地区： 华南农业大学生命科学学院

出　　处： 《植物生理与分子生物学学报》 2006年第2期183-188,共6页

摘　　要： 首先从菠菜叶片中纯化了乙醇酸氧化酶(GO)。通过鉴定反应中氧的消耗以及反应产物 H2O2的生成,证实菠菜 GO 具有氧化光呼吸途径中间代谢物甘油酸的活性。该氧化活性依赖于辅因子 FMN和 FAD,而不依赖核黄素和光黄素;其最适反应pH值为 8.0,Km(甘油酸)值为 7.14mmol/L,kcat值为1.04s-1,活化能为17.29kJ/mol;草酸和丙酮酸对该氧化活性有明显的抑制作用,其中前者为典型的竞争性抑制。进一步通过两底物竞争作图表明:菠菜叶片 GO 氧化甘油酸反应和氧化乙醇酸反应为同一活性中心所催化。菜叶片 GO 氧化甘油酸反应和氧化乙醇酸反应为同一活性中心所催化。 Glycolate oxidase （GO） was purified to homogeneity from leaves of spinach （Spinacia oleracea）. Through detecting the consumption of oxygen and the formation of hydrogen peroxide in the assay solution, it was found that GO could also oxidize glycerate, another metabolite in the photorespiratory pathway, and use FMN and FAD, but not riboflavin and lumiflavin, as its cofactors. The optimum reaction pH, Km for glycerate, Km and activation energy of this oxidizing reaction were determined to be 8.0, 7.14 mmol/L, 1.04 s^-1 and 17.29 kJ/mol, respectively. Oxalate and pyruvate at 5.0 mmol/ L could inhibit the glycerate-oxidizing activity by 34% and 26%, and oxalate acted as a competitive inhibitor of the glycerate oxidation reaction with a Ki of 0.75mmol/ L. By the competition plotting with mixed-substrates, it was indicated that glycolate-oxidizing activity and glycerate-oxidizing activity of GO shared the same active site.

关 键 词： 乙醇酸氧化酶 菠菜 氧化甘油酸活性

领　　域： [生物学]