Huang Jiu-Jiu, Wang Wei-Jun, Ye Jin-Quan, Peng Xin-Xiang
College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
Zhi Wu Sheng Li Yu Fen Zi Sheng Wu Xue Xue Bao. 2006 Apr;32(2):183-8.
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, k(cat) 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 K(i) 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.
乙醇酸氧化酶（GO）从菠菜（Spinacia oleracea）叶片中纯化至同质。通过检测测定溶液中氧气的消耗和过氧化氢的形成，发现GO还可以氧化光呼吸途径中的另一种代谢物甘油酸，并使用FMN和FAD作为其辅因子，但不使用核黄素和发光黄素。该氧化反应的最佳反应pH、甘油酸的Km、k(cat)和活化能分别确定为8.0、7.14 mmol/L、1.04 s(-1)和17.29 kJ/mol。5.0 mmol/L的草酸盐和丙酮酸盐可分别抑制甘油酸氧化活性34%和26%，草酸盐作为甘油酸氧化反应的竞争性抑制剂，K(i)为0.75 mmol/L。通过混合底物竞争作图表明，GO的乙醇酸氧化活性和甘油酸氧化活性共享相同的活性位点。
