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Overview for MACiE Entry M0322

Version history

General Information

EC Number: 1.1.3.9 (A member of the Oxidoreductases, Acting on the CH-OH group of donors, With oxygen as acceptor)

Enzyme Name: galactose oxidiase

Biological Species: Fusarium graminearum (Blight Fungas)

Catalytic Chain UniprotKB Accession Codes:

Representative PDB Code: 1gog - NOVEL THIOETHER BOND REVEALED BY A 1.7 ANGSTROMS CRYSTAL STRUCTURE OF GALACTOSE OXIDASE (Resolution = 1.90 Å).

Catalytic CATH Codes:

"Other" CATH Codes:

Display structure information

Overall Reaction:

Image of primary alcohol

Image of dioxygen

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Image of aldehyde

Image of hydrogen peroxide

primary alcohol
C00226
CHEBI:15734
dioxygen
C00007
CHEBI:15379
aldehyde
C00071
CHEBI:17478
hydrogen peroxide
C00027
CHEBI:16240

Overall Comment: Galactose oxidase is a copper containing enzyme which oxidises primary alcohols to aldehydes by the reduction of molecular oxygen to hydrogen peroxide. The enzyme catalyses the oxidation of many substrates, including dihydroxyacetone, small molecules and olysaccharides by use of a protein radical cofactor, cross-linked Tyr-Cys at the Cu(II) coordination site. Whereas EPR studies suggest the radical to reside on the axial, Tyr-Cys cofactor, modelling experiments, which use density functional theory, suggest the radical to reside on the axial Tyr495. It is thought that the radical transfers to the cross-linked cofactor simultaneously with proton transfer from the substrate [2].


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Stepwise Description of the Reaction

Step 1The coordinated, anionic Tyr residue abstracts a proton from the coordinated primary alcohol substrate.
Step 2A radical is formed at the primary alcohol carbon.
Step 3One electron is transferred from the radical-anion alcohol to the Cu centre, reducing the metal from +2 to +1
Step 4Dioxygen forms a superoxide-radial anion on withdrawing an electron from the Cu centre, oxidising the metal to the +2 state.
Step 5The oxide radical initiates homolytic hydrogen atom abstraction at Tyr272, regenerating the radical tyrosine ligand.
Step 6The anionic peroxide abstracts a proton from Tyr495.
Step 7Hydrogen peroxide is substituted from the Cu(II) coordination sphere by water.

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Catalytic Residues Involved

Type Number Chain Location of Function
Tyr 495 A Side Chain
His 581 A Side Chain
Tyr 272 A Side Chain
His 496 A Side Chain
Cys 228 A Side Chain

Metal Cofactors for M0322

Type Het group Number Chain
copper CU 700 A Overview

References

  1. N. Ito et al. (1991), Nature, 350, 87-90. Novel thioether bond revealed by a 1.7 A crystal structure of galactose oxidase.
    Medline: 2002850
  2. K. J. Humphreys et al. (2008), J. Am. Chem. Soc., 131, 4657-4663. Galactose oxidase as a model for reactivity at a copper superoxide center.
    Medline: 19290629
  3. N. Ito et al. (1994), J. Mol. Biol., 238, 794-814. Crystal structure of a free radical enzyme, galactose oxidase.
    Medline: 94238692

Homologue information for M0322 (1gog)

CSA Homologues

MACiE Homologues (within the PDB)

MACiE Homologues (within UniprotKB/SwissProt)



Entries with at least one Catalytic CATH code in common (different mechanisms):

MACiE Entry Enzyme Name
EC Number
PDB code CATH code Composite
Reaction Similarity
Catalytic Machinery
Similarity
M0149 protein-glutamine gamma-glutamyltransferase
2.3.2.13
1ggt 2.60.40.10
0.07690.5124Compare

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
Link to EzCatDB

GOA logo
extracellular region (cellular component)
cell adhesion (biological process)
oxidoreductase activity (molecular function)
galactose oxidase activity (molecular function)
metal ion binding (molecular function)
oxidation-reduction process (biological process)
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