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.

Peroxidase.

cationic peroxidase; Provisional

Horseradish peroxidase and related secretory plant peroxidases. Secretory peroxidases belong to class III of the plant heme-dependent peroxidase superfamily. All members of the superfamily share a heme prosthetic group and catalyze a multistep oxidative reaction involving hydrogen peroxide as the electron acceptor. Class III peroxidases are found in the extracellular space or in the vacuole in plants where they have been implicated in hydrogen peroxide detoxification, auxin catabolism and lignin biosynthesis, and stress response. Class III peroxidases contain four conserved disulphide bridges and two conserved calcium binding sites.