Glycerate-oxidizing activity of glycolate oxidase from leaves of Spinacia oleracea.
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.
Huang
Jiu-Jiu
JJ
College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
Wang
Wei-Jun
WJ
Ye
Jin-Quan
JQ
Peng
Xin-Xiang
XX
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D005988:Glyceric Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D018515:Plant Leaves / Q000201:enzymology* / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D018724:Spinacia oleracea / Q000201:enzymology* / Q000378:metabolism
D005988:Glyceric Acids; D010940:Plant Proteins; C042971:glyceric acid; D000429:Alcohol Oxidoreductases; C020821:glycollate oxidase