Peroxisomes glycolate oxidase

In leaves glycolate oxidase is restricted to the peroxisomes (Tolbert, 1971) which also contain high catalase and aminotransferase activity. This presumably favors conversion of the glyoxylate to glycine and means that little formate is produced in vivo. 

Glycolate which is generated within the chloroplast is exported and further metabolized within the peroxisomes. Here, the flavin mononucleotide (FMN)-linked enzyme glycolate oxidase catalyzes the conversion to... 

During the operation of glycolate oxidase in normal photorespiration, hydrogen peroxide is formed and is removed by peroxisome-based catalase. The potential toxic action of hydrogen peroxide has already been discussed, and the herbicidal action of aminotriazole is assumed to be, in part, due to catalase inhibition.Mutants of barley that are catalase deficient are rapidly bleached in normal air, in which photorespiration may operate, but will grow normally under C02-enriched air. " It is of interest that in this barley mutant and also in aminotriazole-treated plants, there was an enhancement in the level of leaf glutathione, probably due to increased pressure upon radical-scavenging systems. 

Glyoxylic acid as an intermediate in the glyoxylate cycle is formed by the cleavage of isocitric acid catalyzed by isocitrate lyase. This acid is also an oxidation product of glycolic acid during photorespiration. This reaction is carried out by gly-colate oxidase, which is localized in peroxisomes. 

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