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extracellular superoxide dismutase (EC-SOD, SOD3)
Function:
- destroys O2- radicals which are normally produced within the cells & which are toxic to biological systems
2 O2- + 2 H+ O2 + H2O2
Cofactor:
- binds 1 copper ion per subunit (putative)
- binds 1 Zn+2 per subunit (putative)
Structure:
- homotetramer
- belongs to the Cu-Zn superoxide dismutase family
Compartment:
- secreted
- 99% of EC-SOD is anchored to heparan sulfate proteoglycans in the tissue interstitium
- 1% is located in the vasculature in equilibrium between the plasma & the endothelium
Expression:
- major SOD isoenzyme in extracellular fluids such as plasma, lymph & synovial fluid
Polymorphism:
- variant gly-231 which is found in about 2.2% of individual displays a 10-fold increased plasma EC-SOD content due to reduced heparin-binding affinity & thus the impairment of its binding ability to endothelial cell surface
Interactions
molecular events
General
glycoprotein
oligomerizing protein
secreted protein
superoxide dismutase
Properties
SIZE: entity length = 240 aa
MW = 26 kD
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-18}
Not glycated {41-41}
Not glycated {92-92}
N-glycosylation site {N107}
copper [Cu]-binding site
SITE: 114-114
MOTIF: histidine residue (3)
copper [Cu]-binding site
SITE: 116-116
MOTIF: histidine residue (3)
cysteine residue {C125}
MODIFICATION: cysteine residue {C207}
copper [Cu]-binding site
SITE: 131-131
MOTIF: histidine residue (3)
Zn+2-binding site
SITE: 131-131
Zn+2-binding site
SITE: 139-139
Zn+2-binding site
SITE: 142-142
Zn+2-binding site
SITE: 145-145
copper [Cu]-binding site
SITE: 181-181
MOTIF: histidine residue (3)
cysteine residue {C207}
MODIFICATION: cysteine residue {C125}
Not glycated {238-238}
Database Correlations
OMIM 185490
MORBIDMAP 185490
UniProt P08294
Pfam PF00080
KEGG correlations
ENZYME 1.15.1.1
References
- McNamara & Fridovitch Nature 362:20 1993
- Rosen et al Nature 362:59 1993
- UniProt :accession P08294
- Wikipedia, superoxide dismutase entry
http://en.wikipedia.org/wiki/superoxide_dismutase
Component-of
molecular complex