Overview for MACiE Entry M0239

Version history

General Information

EC Number: (A member of the Oxidoreductases, Acting on a peroxide as acceptor, Peroxidases)

Enzyme Name: peroxidase

Biological Species: Armoracia rusticana (Horseradish)

Catalytic Chain UniprotKB Accession Codes:


Catalytic CATH Codes:

"Other" CATH Codes:

Display structure information

Overall Reaction:

Image of Hydrogen peroxide

Image of Phenol derivative

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Image of Phenolic radical

Image of Water

Hydrogen peroxide
2 Phenol derivative
2 Phenolic radical
2 Water

Overall Comment: Horseradish peroxidase oxidises a broad range of phenolic derivatives. As such no specific substrate has been used in this entry.

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Stepwise Description of the Reaction

Step 1His42 deprotonates hydrogen peroxide. The resulting anion coordinates to the Fe(III) centre of Hem350, displacing water and forming Cpd0.
Step 2The O-O bond of Cpd0 undergoes heterolytic cleavage and the resulting hydroxide is protonated by His42. The porphryin ring and Fe(III) donate an electron each to the oxygen bound to the metal.
Step 3His42 deprotonates water, which then deprotonates the phenolic derivative substrate. The phenolate transfers an electron to the porphyrin ring, forming a phenolic radical and Cpd1.
Step 4The oxygen of Cpd1 is protonated by water, which is in turn protonated by His42.
Step 5The porphyrin ring transfers an electron to the Fe(IV) centre to give an isomer of Cpd1.
Step 6Arg38 transfers a proton to the oxygen of Cpd1.
Step 7Upon binding of the second phenol derivative, Arg38 deprotonates Cpd2.
Step 8His42 deprotonates water, which then deprotonates the phenolic derivative substrate. The phenolate transfers an electron to the porphyrin ring radical, forming a phenolic radical.
Step 9The metal-bound hydroxide is protonated by water, which is in turn protonated by His42.

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Catalytic Residues Involved

Type Number Chain Location of Function
His 42 A Side Chain
Arg 38 A Side Chain
Asn 70 A Side Chain

Metal Cofactors for M0239

Type Het group Number Chain
calcium CA 501 A Overview
calcium CA 502 A Overview
iron HEM 350 A Overview


  1. E. Derat et al. (2006), J. Am. Chem. Soc., 128, 13940-13949. An efficient proton-coupled electron-transfer process during oxidation of ferulic acid by horseradish peroxidase: coming full cycle.
    Medline: 17044722
  2. E. Derat et al. (2006), J. Phys. Chem. B, 110, 10526-10533. The Poulos-Kraut mechanism of Compound I formation in horseradish peroxidase: a QM/MM study.
    Medline: 16722763
  3. A. Henriksen et al. (1999), J. Biol. Chem., 274, 35005-35011. The structures of the horseradish peroxidase C-ferulic acid complex and the ternary complex with cyanide suggest how peroxidases oxidize small phenolic substrates.
    Medline: 10574977
  4. K. Meno et al. (2002), Acta Crystallogr. D Biol. Crystallogr., 58, 1803-1812. Structural analysis of the two horseradish peroxidase catalytic residue variants H42E and R38S/H42E: implications for the catalytic cycle.
    Medline: 12351824
  5. M. Gajhede (2000), Biochem. Soc. Trans., 29, 91-98. Plant peroxidases: substrate complexes with mechanistic implications.
    Medline: 11356134

Homologue information for M0239 (7atj)

CSA Homologues

MACiE Homologues (within the PDB)

MACiE Homologues (within UniprotKB/SwissProt)

Links to this entry in other databases

Link to EC-PDB-SUM Link to PDB-SUM Link to RCSB PDB Link to PDBe Link to CSA
Link to MetaCyc Link to KEGG Link to BRENDA Link to ExplorENZ

GOA logo
peroxidase activity (molecular function)
extracellular region (cellular component)
vacuole (cellular component)
response to oxidative stress (biological process)
oxidoreductase activity (molecular function)
heme binding (molecular function)
hydrogen peroxide catabolic process (biological process)
metal ion binding (molecular function)
oxidation-reduction process (biological process)