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.

The recognition of glycolate oxidase apoprotein with flavin analogs in higher plants.

The dependence of glycolate oxidase apoprotein (apoGO) activity on flavin analogs was surveyed in 9 higher plants from 7 families. Activities of all apoGOs depended not only on flavin mononucleotide (FMN) but also on flavin adenine dinucleotide (FAD), but not on riboflavin. The kinetic analysis showed that FMN was the optimum cofactor for apoGO from leaves of Brassica campestris.