DB code: T00018

CATH domain 3.10.120.10 : Flavocytochrome B2; Chain A, domain 1 Catalytic domain
3.90.420.10 : Sulfite Oxidase; Chain A, domain 2 Catalytic domain
2.60.40.650 : Immunoglobulin-like
E.C. 1.8.3.1
CSA 1sox
M-CSA 1sox
MACiE M0121

CATH domain Related DB codes (homologues)
3.10.120.10 : Flavocytochrome B2; Chain A, domain 1 D00014

Uniprot Enzyme Name
UniprotKB Protein name Synonyms Pfam RefSeq
P07850 Sulfite oxidase
EC 1.8.3.1
PF00173 (Cyt-b5)
PF03404 (Mo-co_dimer)
PF00174 (Oxidored_molyb)
[Graphical View]
P51687 Sulfite oxidase, mitochondrial
EC 1.8.3.1
PF00173 (Cyt-b5)
PF03404 (Mo-co_dimer)
PF00174 (Oxidored_molyb)
[Graphical View]
NP_000447.2 (Protein)
NM_000456.2 (DNA/RNA sequence)
NP_001027558.1 (Protein)
NM_001032386.1 (DNA/RNA sequence)
NP_001027559.1 (Protein)
NM_001032387.1 (DNA/RNA sequence)

KEGG enzyme name
sulfite oxidase

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
P51687 SUOX_HUMAN Sulfite + O(2) + H(2)O = sulfate + H(2)O(2). Homodimer (By similarity). Mitochondrion intermembrane space. Binds 1 protoheme group. Molybdenum (molybdopterin).
P07850 SUOX_CHICK Sulfite + O(2) + H(2)O = sulfate + H(2)O(2). Homodimer. Mitochondrion intermembrane space. Binds 1 protoheme group. Molybdenum (molybdopterin).

KEGG Pathways
Map code Pathways E.C.
MAP00920 Sulfur metabolism

Compound table
Cofactors Substrates Products Intermediates
KEGG-id C00150 C05924 C00032 C00094 C00007 C00001 C00059 C00027
E.C.
Compound Molybdenum Molybdopterin Heme Sulfite O2 H2O Sulfate H2O2
Type heavy metal amide group,amine group,aromatic ring (with nitrogen atoms),carbohydrate,phosphate group/phosphate ion,sulfhydryl group aromatic ring (with nitrogen atoms),carboxyl group,heavy metal sulfite others H2O sulfate group others
ChEBI 28685
44074
17627
26355
48854
15379
26689
27140
15377
26836
16240
PubChem 23932
444331
1100
22132154
977
22247451
962
1118
22066174
5152822
22326046
784
1soxA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Bound:HEM Unbound Unbound Unbound Unbound
1soxB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Bound:HEM Unbound Unbound Unbound Unbound
1mj4A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Bound:HEM Unbound Unbound Unbound Unbound
1soxA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:_MO-MTE Bound:MTE-_MO Unbound Unbound Unbound Bound:SO4_503 Unbound
1soxB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:_MO-MTE Bound:MTE-_MO Unbound Unbound Unbound Bound:SO4_503 Unbound
1soxA03 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound Unbound Unbound Unbound
1soxB03 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.
Swiss-prot;P07850

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1soxA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain HIS 40;HIS 65(Heme iron binding)
1soxB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain HIS 40;HIS 65(Heme iron binding)
1mj4A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain HIS 40;HIS 65(Heme iron binding)
1soxA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain TYR 322 CYS 185(Molybdenum binding)
1soxB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain TYR 322 CYS 185(Molybdenum binding)
1soxA03 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1soxB03 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain

References for Catalytic Mechanism
References Sections No. of steps in catalysis
[12]
p.976-981
[14]
Scheme 1, p.6672-6676
[15]
Fig.1, Fig.2, Fig.8, Fig.9
[19]
Scheme 1
[20]
Scheme 2, p.69
[26]
Scheme 1
[28]
p.363-366
[29]
[30]
Fig.2
[31]
Scheme 1
[32]
Fig.1, Fig.2
[35]
Fig.7, p.15112-15113

References
[1]
Resource
Comments
Medline ID
PubMed ID 6258584
Journal Biochem J
Year 1980
Volume 191
Pages 285-8
Authors Gutteridge S, Lamy MT, Bray RC
Title The nature of the phosphate inhibitor complex of sulphite oxidase from electron-paramagnetic-resonance studies using oxygen-17.
Related PDB
Related UniProtKB
[2]
Resource
Comments
Medline ID
PubMed ID 6249254
Journal Biochem J
Year 1980
Volume 185
Pages 397-403
Authors Lamy MT, Gutteridge S, Bary RC
Title Electron-paramagnetic-resonance parameters of molybdenum(V) in sulphite oxidase from chicken liver.
Related PDB
Related UniProtKB
[3]
Resource
Comments
Medline ID
PubMed ID 6244290
Journal J Biol Chem
Year 1980
Volume 255
Pages 2694-9
Authors Coughlan MP, Johnson JL, Rajagopalan KV
Title Mechanisms of inactivation of molybdoenzymes by cyanide.
Related PDB
Related UniProtKB
[4]
Resource
Comments
Medline ID
PubMed ID 6282260
Journal Biochem J
Year 1982
Volume 201
Pages 241-3
Authors Bray RC, Lamy MT, Gutteridge S, Wilkinson T
Title Evidence from electron-paramagnetic-resonance spectroscopy for a complex of sulphite ions with the molybdenum centre of sulphite oxidase.
Related PDB
Related UniProtKB
[5]
Resource
Comments
Medline ID
PubMed ID 6307274
Journal Biochem J
Year 1983
Volume 211
Pages 227-36
Authors Bray RC, Gutteridge S, Lamy MT, Wilkinson T
Title Equilibria amongst different molybdenum (V)-containing species from sulphite oxidase. Evidence for a halide ligand of molybdenum in the low-pH species.
Related PDB
Related UniProtKB
[6]
Resource
Comments
Medline ID
PubMed ID 6546929
Journal J Biol Chem
Year 1984
Volume 259
Pages 5414-22
Authors Johnson JL, Hainline BE, Rajagopalan KV, Arison BH
Title The pterin component of the molybdenum cofactor. Structural characterization of two fluorescent derivatives.
Related PDB
Related UniProtKB
[7]
Resource
Comments
Medline ID
PubMed ID 3806088
Journal J Inorg Biochem
Year 1986
Volume 28
Pages 107-23
Authors Mitchell PC
Title Molybdenum in enzymatic and heterogeneous catalysis.
Related PDB
Related UniProtKB
[8]
Resource
Comments
Medline ID
PubMed ID 3680253
Journal J Biol Chem
Year 1987
Volume 262
Pages 16357-63
Authors Kramer SP, Johnson JL, Ribeiro AA, Millington DS, Rajagopalan KV
Title The structure of the molybdenum cofactor. Characterization of di-(carboxamidomethyl)molybdopterin from sulfite oxidase and xanthine oxidase.
Related PDB
Related UniProtKB
[9]
Resource
Comments
Medline ID
PubMed ID 2851985
Journal Biochem J
Year 1988
Volume 256
Pages 307-9
Authors George GN, Prince RC, Kipke CA, Sunde RA, Enemark JH
Title The nature of the phosphate complex of sulphite oxidase from electron-paramagnetic-resonance studies.
Related PDB
Related UniProtKB
[10]
Resource
Comments
Medline ID
PubMed ID 2548601
Journal Biochemistry
Year 1989
Volume 28
Pages 5075-80
Authors George GN, Kipke CA, Prince RC, Sunde RA, Enemark JH, Cramer SP
Title Structure of the active site of sulfite oxidase. X-ray absorption spectroscopy of the Mo(IV), Mo(V), and Mo(VI) oxidation states.
Related PDB
Related UniProtKB
[11]
Resource
Comments
Medline ID
PubMed ID 8190702
Journal Pharmacol Toxicol
Year 1994
Volume 74
Pages 136-40
Authors Constantin D, Mehrotra K, Jernstrom B, Tomasi A, Moldeus P
Title Alternative pathways of sulfite oxidation in human polymorphonuclear leukocytes.
Related PDB
Related UniProtKB
[12]
Resource
Comments X-RAY CRYSTALLOGRAPHY (1.9 ANGSTROMS), AND SEQUENCE REVISION TO 152.
Medline ID 98088796
PubMed ID 9428520
Journal Cell
Year 1997
Volume 91
Pages 973-83
Authors Kisker C, Schindelin H, Pacheco A, Wehbi WA, Garrett RM, Rajagopalan KV, Enemark JH, Rees DC
Title Molecular basis of sulfite oxidase deficiency from the structure of sulfite oxidase.
Related PDB 1sox
Related UniProtKB P07850
[13]
Resource
Comments
Medline ID
PubMed ID 9652170
Journal Prog Biophys Mol Biol
Year 1997
Volume 68
Pages 121-44
Authors Romao MJ, Knablein J, Huber R, Moura JJ
Title Structure and function of molybdopterin containing enzymes.
Related PDB
Related UniProtKB
[14]
Resource
Comments
Medline ID
PubMed ID 10350486
Journal Biochemistry
Year 1999
Volume 38
Pages 6668-77
Authors Brody MS, Hille R
Title The kinetic behavior of chicken liver sulfite oxidase.
Related PDB
Related UniProtKB
[15]
Resource
Comments
Medline ID
PubMed ID 10555573
Journal J Biol Inorg Chem
Year 1999
Volume 4
Pages 390-401
Authors Pacheco A, Hazzard JT, Tollin G, Enemark JH
Title The pH dependence of intramolecular electron transfer rates in sulfite oxidase at high and low anion concentrations.
Related PDB
Related UniProtKB
[16]
Resource
Comments
Medline ID
PubMed ID 11185564
Journal Arch Biochem Biophys
Year 2000
Volume 383
Pages 281-7
Authors Temple CA, Graf TN, Rajagopalan KV
Title Optimization of expression of human sulfite oxidase and its molybdenum domain.
Related PDB
Related UniProtKB
[17]
Resource
Comments
Medline ID
PubMed ID 11196982
Journal Inorg Chem
Year 2000
Volume 39
Pages 4989-92
Authors Astashkin AV, Cosper MM, Raitsimring AM, Enemark JH
Title ESEEM and mims ENDOR spectroscopies of cis,trans-(L-N2S2)MoVO(SCH2Ph): detection of the two benzylthiolate alpha protons.
Related PDB
Related UniProtKB
[18]
Resource
Comments
Medline ID
PubMed ID 11229572
Journal Inorg Chem
Year 2000
Volume 39
Pages 525-31
Authors Mader ML, Carducci MD, Enemark JH
Title Analogues for the molybdenum center of sulfite oxidase: oxomolybdenum(V) complexes with three thiolate sulfur donor atoms.
Related PDB
Related UniProtKB
[19]
Resource
Comments
Medline ID
PubMed ID 11151370
Journal Inorg Chem
Year 2000
Volume 39
Pages 5697-706
Authors McNaughton RL, Tipton AA, Rubie ND, Conry RR, Kirk ML
Title Electronic structure studies of oxomolybdenum tetrathiolate complexes: origin of reduction potential differences and relationship to cysteine-molybdenum bonding in sulfite oxidase.
Related PDB
Related UniProtKB
[20]
Resource
Comments
Medline ID
PubMed ID 10830849
Journal J Inorg Biochem
Year 2000
Volume 79
Pages 67-74
Authors Thapper A, Lorber C, Fryxelius J, Behrens A, Nordlander E
Title Synthesis and reactivity studies of model complexes for molybdopterin-dependent enzymes.
Related PDB
Related UniProtKB
[21]
Resource
Comments
Medline ID
PubMed ID 11516283
Journal J Am Chem Soc
Year 2001
Volume 123
Pages 8343-9
Authors Lim BS, Willer MW, Miao M, Holm RH
Title Monodithiolene molybdenum(V, VI) complexes: a structural analogue of the oxidized active site of the sulfite oxidase enzyme family.
Related PDB
Related UniProtKB
[22]
Resource
Comments
Medline ID
PubMed ID 11598126
Journal J Biol Chem
Year 2001
Volume 276
Pages 46989-94
Authors Eilers T, Schwarz G, Brinkmann H, Witt C, Richter T, Nieder J, Koch B, Hille R, Hansch R, Mendel RR
Title Identification and biochemical characterization of Arabidopsis thaliana sulfite oxidase. A new player in plant sulfur metabolism.
Related PDB
Related UniProtKB
[23]
Resource
Comments
Medline ID
PubMed ID 11980485
Journal Biochemistry
Year 2002
Volume 41
Pages 5816-21
Authors Feng C, Kedia RV, Hazzard JT, Hurley JK, Tollin G, Enemark JH
Title Effect of solution viscosity on intramolecular electron transfer in sulfite oxidase.
Related PDB
Related UniProtKB
[24]
Resource
Comments
Medline ID
PubMed ID 12022845
Journal J Am Chem Soc
Year 2002
Volume 124
Pages 6109-18
Authors Astashkin AV, Raitsimring AM, Feng C, Johnson JL, Rajagopalan KV, Enemark JH
Title Pulsed EPR studies of nonexchangeable protons near the Mo(V) center of sulfite oxidase: direct detection of the alpha-proton of the coordinated cysteinyl residue and structural implications for the active site.
Related PDB
Related UniProtKB
[25]
Resource
Comments
Medline ID
PubMed ID 12296723
Journal J Am Chem Soc
Year 2002
Volume 124
Pages 11612-3
Authors Elliott SJ, McElhaney AE, Feng C, Enemark JH, Armstrong FA
Title A voltammetric study of interdomain electron transfer within sulfite oxidase.
Related PDB
Related UniProtKB
[26]
Resource
Comments
Medline ID
PubMed ID 12148977
Journal J Am Chem Soc
Year 2002
Volume 124
Pages 9006-7
Authors Peariso K, McNaughton RL, Kirk ML
Title Active-site stereochemical control of oxygen atom transfer reactivity in sulfite oxidase.
Related PDB
Related UniProtKB
[27]
Resource
Comments
Medline ID
PubMed ID 11935358
Journal J Biol Inorg Chem
Year 2002
Volume 7
Pages 338-50
Authors Codd R, Astashkin AV, Pacheco A, Raitsimring AM, Enemark JH
Title Pulsed ELDOR spectroscopy of the Mo(V)/Fe(III) state of sulfite oxidase prepared by one-electron reduction with Ti(III) citrate.
Related PDB
Related UniProtKB
[28]
Resource
Comments
Medline ID
PubMed ID 12114025
Journal Trends Biochem Sci
Year 2002
Volume 27
Pages 360-7
Authors Hille R
Title Molybdenum and tungsten in biology.
Related PDB
Related UniProtKB
[29]
Resource
Comments X-ray crystallography
Medline ID
PubMed ID 12832761
Journal Acta Crystallogr D Biol Crystallogr
Year 2003
Volume 59
Pages 1183-91
Authors Rudolph MJ, Johnson JL, Rajagopalan KV, Kisker C
Title The 1.2 A structure of the human sulfite oxidase cytochrome b(5) domain.
Related PDB 1mj4
Related UniProtKB
[30]
Resource
Comments
Medline ID
PubMed ID 12950200
Journal Inorg Chem
Year 2003
Volume 42
Pages 5531-6
Authors Jalilehvand F, Lim BS, Holm RH, Hedman B, Hodgson KO
Title X-ray absorption spectroscopy of a structural analogue of the oxidized active sites in the sulfite oxidase enzyme family and related molybdenum(V) complexes.
Related PDB
Related UniProtKB
[31]
Resource
Comments
Medline ID
PubMed ID 14514295
Journal Inorg Chem
Year 2003
Volume 42
Pages 6194-203
Authors Peariso K, Chohan BS, Carrano CJ, Kirk ML
Title Synthesis and EPR characterization of new models for the one-electron reduced molybdenum site of sulfite oxidase.
Related PDB
Related UniProtKB
[32]
Resource
Comments
Medline ID
PubMed ID 12424234
Journal J Biol Chem
Year 2003
Volume 278
Pages 2913-20
Authors Feng C, Wilson HL, Hurley JK, Hazzard JT, Tollin G, Rajagopalan KV, Enemark JH
Title Role of conserved tyrosine 343 in intramolecular electron transfer in human sulfite oxidase.
Related PDB
Related UniProtKB
[33]
Resource
Comments
Medline ID
PubMed ID 14527393
Journal Structure (Camb)
Year 2003
Volume 11
Pages 1251-63
Authors Schrader N, Fischer K, Theis K, Mendel RR, Schwarz G, Kisker C
Title The crystal structure of plant sulfite oxidase provides insights into sulfite oxidation in plants and animals.
Related PDB 1ogp
Related UniProtKB
[34]
Resource
Comments
Medline ID
PubMed ID 14989655
Journal Inorg Chem
Year 2004
Volume 43
Pages 1625-37
Authors McNaughton RL, Helton ME, Cosper MM, Enemark JH, Kirk ML
Title Nature of the oxomolybdenum-thiolate pi-bond: implications for Mo-S bonding in sulfite oxidase and xanthine oxidase.
Related PDB
Related UniProtKB
[35]
Resource
Comments
Medline ID
PubMed ID 14729666
Journal J Biol Chem
Year 2004
Volume 279
Pages 15105-13
Authors Wilson HL, Rajagopalan KV
Title The role of tyrosine 343 in substrate binding and catalysis by human sulfite oxidase.
Related PDB
Related UniProtKB

Comments
This enzyme is composed of Molybdenum (Mo) catalytic domain and Heme-Fe catalytic domain. It catalyzes the following reactions during the catalytic cycle (see [15]):
(A) Two-electron oxidation of SO3(2-) to SO4(2-) at the Mo(VI) catalytic site.
(B) Intramolecular electron transfer (IET) from the Mo(IV) catalytic site to the Heme-Fe(III) catalytic site.
(C) One-electron transfer from the Heme-Fe(II) catalytic site to exogenous (cyt c)ox.
(D) IET from the Mo(V) catalytic site to the Heme-Fe(III) catalytic site.
(E) One-electron transfer from the Heme-Fe(II) catalytic site to exogenous (cyt c)ox.

Created Updated
2004-12-27 2009-02-26