CAJ | 학술논문

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7.14 mmol/L,kcat值为1.04 s-1,活化能为17.29 kJ/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.
수선종파채협편중순화료을순산양화매(GO).통과감정반응중양적소모이급반응산물H2O2적생성,증실파채GO구유양화광호흡도경중간대사물감유산적활성.해양화활성의뢰우보인자FMN화FAD,이불의뢰핵황소화광황소;기최괄반응pH치위8.0,Km(감유산)치위7.14 mmol/L,kcat치위1.04 s-1,활화능위17.29 kJ/mol;초산화병동산대해양화활성유명현적억제작용,기중전자위전형적경쟁성억제.진일보통과량저물경쟁작도표명:파채협편GO양화감유산반응화양화을순산반응위동일활성중심소최화.
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,kcat and activation energy of this oxidizing reaction were determined to be 8.0, 7.14 mmol/L, 1.04 s-1 and 17.29k J/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 0.75 mmol/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.