Function 
Ascorbate peroxidase (APX) catalyzes the conversion of ascorbate and hydrogen peroxide to dehydroascorbate and water thus detoxifying hydrogen peroxide.  APX is involved in the glutathione-ascorbate cycle.  APX is accumulated in plants in response to heat and drought stress.  APX contains a heme group.
  Relevance 
APX is part of plants antioxidant defense.  APX converts H2O2 to water using ascorbate as an electron donor.  APX is used in electron microscopy as a genetic tag which can be stained independently of light activation.
  Structural highlights 
The  of APX contains a  and confers stability to the Fe state in the heme. [1]
 3D structures of ascorbate peroxidase
Ascorbate peroxidase 3D structures