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ENZYME

ENZYME entry: EC 1.11.1.14

Accepted Name
lignin peroxidase
Alternative Name(s)
diarylpropane oxygenase
diarylpropane peroxidase
ligninase I
LiP
Reaction catalysed
  • 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol + H2O2 = 3,4-dimethoxybenzaldehyde + glycolaldehyde + guaiacol + H2O
  • 2 (3,4-dimethoxyphenyl)methanol + H2O2 = 2 (3,4-dimethoxyphenyl)methanol radical + 2 H2O
Comment(s)
  • Involved in the oxidative breakdown of lignin by white-rot basidiomycete fungi.
  • The reaction involves an initial oxidation of the heme iron by hydrogen peroxide, forming compound I (Fe(IV)=O radical cation) at the active site.
  • A single one-electron reduction of compound I by an electron derived from a substrate molecule yields compound II (Fe(IV)=O non-radical cation), followed by a second one-electron transfer that returns the enzyme to the ferric oxidation state.
  • The electron transfer events convert the substrate molecule into a transient cation radical intermediate that fragments spontaneously.
  • The enzyme can act on a wide range of aromatic compounds, including methoxybenzenes and nonphenolic beta-O-4 linked arylglycerol beta- aryl ethers, but cannot act directly on the lignin molecule, which is too large to fit into the active site.
  • However larger lignin molecules can be degraded in the presence of veratryl alcohol.
  • It has been suggested that the free radical that is formed when the enzyme acts on veratryl alcohol can diffuse into the lignified cell wall, where it oxidizes lignin and other organic substrates.
  • In the presence of high concentration of hydrogen peroxide and lack of substrate, the enzyme forms a catalytically inactive form (compound III).
  • This form can be rescued by interaction with two molecules of the free radical products.
  • In the case of veratryl alcohol, such an interaction yields two molecules of veratryl aldehyde.
Cross-references
BRENDA1.11.1.14
EC2PDB1.11.1.14
ExplorEnz1.11.1.14
PRIAM enzyme-specific profiles1.11.1.14
KEGG Ligand Database for Enzyme Nomenclature1.11.1.14
IUBMB Enzyme Nomenclature1.11.1.14
IntEnz1.11.1.14
MEDLINEFind literature relating to 1.11.1.14
MetaCyc1.11.1.14
Rhea expert-curated reactions1.11.1.14
UniProtKB/Swiss-Prot
P49012, LIG2_PHACHP21764, LIG3_PHACHP11542, LIG4_PHACH
P11543, LIG5_PHACHP50622, LIG6_PHACHP06181, LIG8_PHACH
P31837, LIGA_PHACHP20011, LIGA_TRAVEP31838, LIGB_PHACH
P20012, LIGB_TRAVEP20013, LIGC_TRAVEP20010, LIG_PHLRA

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