GO:0020037 heme binding

GO:0020037 heme binding
Synonyms: haem binding
Definition: Interacting selectively and non-covalently with heme, any compound of iron complexed in a porphyrin (tetrapyrrole) ring.
血红素结合
定义：选择性的与血红素共价结合，卟啉（四吡咯）环中铁络合的任何化合物

Cross-references
InterPro IPR000823 Plant peroxidase EC: 1.11.1.7

Description

Peroxidases are haem-containing enzymes that use hydrogen peroxide as the electron acceptor to catalyse a number of oxidative reactions. Most haem peroxidases follow the reaction scheme:

Fe³⁺ + H₂O₂ --> [Fe⁴⁺=O]R' (Compound I) + H₂O [Fe⁴⁺=O]R' + substrate --> [Fe⁴⁺=O]R (Compound II) + oxidised substrate [Fe⁴⁺=O]R + substrate --> Fe³⁺ + H₂O + oxidised substrate

In this mechanism, the enzyme reacts with one equivalent of H₂O₂ to give [Fe⁴⁺=O]R' (compound I). This is a two-electron oxidation/reduction reaction where H₂O₂ is reduced to water and the enzyme is oxidised. One oxidising equivalent resides on iron, giving the oxyferryl ^[1] intermediate, while in many peroxidases the porphyrin (R) is oxidised to the porphyrin pi-cation radical (R'). Compound I then oxidises an organic substrate to give a substrate radical ^[2].
Peroxidases are found in bacteria, fungi, plants and animals and can be viewed as members of a superfamily consisting of 3 major classes. Class III comprises the secretory plant peroxidases, which have multiple tissue-specific functions e.g.,

• removal of hydrogen peroxide from chloroplasts and cytosol;
• oxidation of toxic compounds; biosynthesis of the cell wall;
• defence responses towards wounding; indole-3-acetic acid (IAA) catabolism;
• ethylene biosynthesis; and so on.
  The wide spectrum of peroxidase activity, coupled with the participation in various physiological processes, is in keeping with its relative lack of specificity for substrates and the occurrence of a variety of isozymes. Plant peroxidases are monomeric glycoproteins containing 4 conserved disulphide bridges and 2 calcium ions. The 3D structure of peanut peroxidase has been shown to possess the same helical fold as class I and II peroxidases
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