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

More general terms

• superoxide dismutase
• glycoprotein
• secreted protein
• oligomerizing protein

Database

• UniProt: http://www.uniprot.org/uniprot/P08294.html
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6649
• OMIM: https://mirror.omim.org/entry/185490