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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this work was to determine the compartmentation of antioxidants between the bundle-sheath and mesophyll cells of maize (Zea mays L.) leaves. Rapid fractionation of the mesophyll compartment was used to minimize modifications in the antioxidant status and composition due to extraction procedures. The purity of the mesophyll isolates was assessed via the distribution of enzyme and metabolite markers. Ribulose-1,5 bisphosphate and ribulose-1,5-bisphosphate carboxylase/oxygenase were used as bundle-sheath markers and phosphoenolpyruvate carboxylase was used as the mesophyll marker enzyme. Glutathione reductase and dehydroascorbate reductase were almost exclusively localized in the mesophyll tissue, whereas ascorbate, ascorbate peroxidase, and superoxide dismutase were largely absent from the mesophyll fraction. Catalase, reduced glutathione, and monodehydroascorbate reductase were found to be approximately equally distributed between the two cell types. It is interesting that, whereas H2O2 levels were relatively high in maize leaves, this oxidant was largely restricted to the mesophyll compartment. We conclude that the antioxidants in maize leaves are partitioned between the two cell types according to the availability of reducing power and NADPH and that oxidized glutathione and dehydroascorbate produced in the bundle-sheat tissues have to be transported to the mesophyll for re-reduction to their reduced forms.
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PMID:Differential Localization of Antioxidants in Maize Leaves. 1222 57

Ribulose-1,5-bisphosphate carboxylase/oxygenase, catalase, glycolate oxidase, and hydroxypyruvate reductase activities on a protein and fresh weight basis were measured over seven stages of tomato fruit development and ripening. Ribulose-1,5-bisphosphate carboxylase decreased steadily during fruit development from 23 +/- 8 nmoles per minute per milligram protein at the mature green stage to 13.4 +/- 2 at the table ripe stage. There was no change in partially purified preparations of the enzyme in the ratio of carboxylase to oxygenase activity, which was about 10. Catalase activity reached a maximum during the climacteric, simultaneously with increased ethylene and CO(2) formation. Glycolate oxidase activity decreased during early stages of development and was barely detectable at the climacteric. Hydroxypyruvate reductase, associated with serine formation by the glycerate pathway, increased in specific activity during early stages of tomato fruit ripening. In the fruit of the rin tomato mutant, which does not ripen normally, none of these changes in enzyme activity occurred.
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PMID:Changes in Activity of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase and Three Peroxisomal Enzymes during Tomato Fruit Development and Ripening. 1666 Jul 53