L-ascorbate peroxidase

L-ascorbate peroxidase

Peroxidase.

Heme-dependent peroxidases similar to plant peroxidases. Along with animal peroxidases, these enzymes belong to a group of peroxidases containing a heme prosthetic group (ferriprotoporphyrin IX), which catalyzes a multistep oxidative reaction involving hydrogen peroxide as the electron acceptor. The plant peroxidase-like superfamily is found in all three kingdoms of life and carries out a variety of biosynthetic and degradative functions. Several sub-families can be identified. Class I includes intracellular peroxidases present in fungi, plants, archaea and bacteria, called catalase-peroxidases, that can exhibit both catalase and broad-spectrum peroxidase activities depending on the steady-state concentration of hydrogen peroxide. Catalase-peroxidases are typically comprised of two homologous domains that probably arose via a single gene duplication event. Class II includes ligninase and other extracellular fungal peroxidases, while class III is comprised of classic extracellular plant peroxidases, like horseradish peroxidase.

Ascorbate peroxidases and cytochrome C peroxidases. Ascorbate peroxidases are a subgroup of heme-dependent peroxidases of the plant superfamily that share a heme prosthetic group and catalyze a multistep oxidative reaction involving hydrogen peroxide as the electron acceptor. Along with related catalase-peroxidases, ascorbate peroxidases belong to class I of the plant superfamily. Ascorbate peroxidases are found in the chloroplasts and/or cytosol of algae and plants, where they have been shown to control the concentration of lethal hydrogen peroxide molecules. The yeast cytochrome c peroxidase is a divergent member of the family; it forms a complex with cytochrome c to catalyze the reduction of hydrogen peroxide to water.