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Overview for MACiE Entry M0144

Version history

General Information

EC Number: 1.20.98.1 (A member of the Oxidoreductases, Acting on phosphorus or arsenic in donors, With other, known, acceptors)

Enzyme Name: arsenite oxidase

Biological Species: Alcaligenes faecalis (Bacteria)

Catalytic Chain UniprotKB Accession Codes:

  • Q7SIF4 - Arsenite oxidase large subunit
  • Q7SIF3 - Arsenite oxidase small subunit

Representative PDB Code: 1g8k - CRYSTAL STRUCTURE ANALYSIS OF ARSENITE OXIDASE FROM ALCALIGENESFAECALIS (Resolution = 1.64 Å).

Catalytic CATH Codes:

  • 3.40.228.10 - Dimethylsulfoxide Reductase, domain 2
  • 2.102.10.10 - 'Rieske'-like iron-sulphur domains
  • Unassigned Domain

"Other" CATH Codes:

Display structure information

Overall Reaction:

Image of oxidised azurin

Image of water

Image of arsenite

right arrow

Image of proton

Image of reduced azurin

Image of arsenate

oxidised azurin
C05357
water
C00001
CHEBI:15377
arsenite
C06697
CHEBI:29243
2 proton
C00080
CHEBI:24636
reduced azurin
C05358
arsenate
C11215
CHEBI:48597

It is unknown whether this reaction is reversible or not.

Overall Comment: The Mo atom is bound to two pterin cofactors (MGD5001 and MGD5002 in the crystal structure) but only one of them is shown in the diagrams for easy of readability. The electron acceptors for this reaction are either azurin or cytochrome c.

The enzyme does not return to a state in which it can catalyse another reaction


View similar reactions


Stepwise Description of the Reaction

Step 1Arsenic of the arsenite substrate attacks one of the molybdenum coordinating oxo groups, resulting in a Mo(VI) to Mo(IV) reduction.
Step 2The attacking oxo group forms a second bond to the arsenic, forming the product arsenate and resulting in the loss of the oxo group from the molybdenum complex and the remaining oxo group binding in a much stronger interaction.
Step 3An unidentified base activates water to attack the Mo(IV), forming a hydroxide group in place of the lost oxo group in a nucleophilic addition to the Mo(IV).
Step 4A second unidentified base deprotonates the Mo-bound hydroxide, reforming the oxo group. This results in a single electron transfer through the pterin portion of the cofactor, main chain carbonyl of Ser238, thiolate of Cys24, an iron-sulfur cluster, the peptide bond of Ser99-Ser98, His62B, a second iron-sulfur complex and His81B and finally yields the electron to a bound azurin and resulting in Mo(V).
Step 5The second single electron is transferred from Mo(V) through the pterin portion of the cofactor, main chain carbonyl of Ser238, thiolate of Cys24, an iron-sulfur cluster, the peptide bond of Ser99-Ser98, His62B, a second iron-sulfur complex and His81B and finally yields the electron to a bound azurin. This regenerates the enzyme's Mo(VI) oxidation state.

View similar reactions (composite manual annotation)


Catalytic Residues Involved

Type Number Chain Location of Function
Cys 24 A Side Chain
Ser 98 A Main Chain Carbonyl
Ser 99 A Main Chain Amide
Ser 238 A Main Chain Carbonyl
His 62 B Side Chain
His 81 B Side Chain

Organic Cofactors for M0144

Type Identity Chain
Molybdopterin guanosine dinucleotide MGD 5002 Overview

Metal Cofactors for M0144

Type Het group Number Chain
molybdenum 4MO 5004 x Overview
iron FS3 5005 x Overview
iron FES 5006 x Overview

References

  1. P. J. Ellis et al. (2001), Structure, 9, 125-132. Crystal structure of the 100 kDa arsenite oxidase from Alcaligenes faecalis in two crystal forms at 1.64 A and 2.03 A.
    Medline: 11250197
  2. T. Conrads et al. (2002), J. Am. Chem. Soc., 124, 11276-11277. The active site of arsenite oxidase from Alcaligenes faecalis.
    Medline: 12236735
  3. K. R. Hoke et al. (2004), Biochemistry, 43, 1667-1674. Electrochemical studies of arsenite oxidase: an unusual example of a highly cooperative two-electron molybdenum center.
    Medline: 14769044

Homologue information for M0144 (1g8k)

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
M0276 nitrate reductase
1.7.99.4
1ogy 3.40.228.10
0.0.0.0
3.40.50.740
2.40.40.20
0.250.0526Compare
M0208 ubiquinol-cytochrome-c reductase
1.10.2.2
1ezv 2.102.10.10
0.06870.4199Compare
M0130 naphthalene 1,2-dioxygenase
1.14.12.12
1ndo 2.102.10.10
0.09370.2399Compare

View a comparison of the other reactions in MACiE with the CATH domain 0.0.0.0

View a comparison of the other reactions in MACiE with the CATH domain 2.102.10.10


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
binding (molecular function)
ubiquinol-cytochrome-c reductase activity (molecular function)
membrane (cellular component)
oxidoreductase activity (molecular function)
molybdenum ion binding (molecular function)
metal ion binding (molecular function)
arsenate reductase (azurin) activity (molecular function)
iron-sulfur cluster binding (molecular function)
2 iron, 2 sulfur cluster binding (molecular function)
3 iron, 4 sulfur cluster binding (molecular function)
oxidation-reduction process (biological process)
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