Plays a key role in hydrogen peroxide removal. H2O2 + L-ascorbate = 2 H2O + L-dehydroascorbate Binds 1 heme b (iron(II)-protoporphyrin IX) group. Expressed in leaves, stems and flowers. Down-regulated by hydrogen peroxide in leaves. Binds one cation per subunit; probably K(+), but might also be Ca(2+). Belongs to the peroxidase family. Ascorbate peroxidase subfamily. According to PubMed:15599508, it may be peroxisomal. There is however no experimental evidence to prove this.