Superoxide dismutase

related topics
{acid, form, water}
{disease, patient, cell}
{math, energy, light}
{food, make, wine}
{law, state, case}

Superoxide dismutases (SOD, EC 1.15.1.1) are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide. As such, they are an important antioxidant defense in nearly all cells exposed to oxygen. One of the exceedingly rare exceptions is Lactobacillus plantarum and related lactobacilli, which use a different mechanism.

Contents

Reaction

The SOD-catalysed dismutation of superoxide may be written with the following half-reactions :

  • M(n+1)+-SOD + O2 → Mn+-SOD + O2
  • Mn+-SOD + O2 + 2H+ → M(n+1)+-SOD + H2O2.

where M = Cu (n=1) ; Mn (n=2) ; Fe (n=2) ; Ni (n=2).

In this reaction the oxidation state of the metal cation oscillates between n and n+1.

Types

General

Discovered by Irwin Fridovich and Joe McCord, SOD enzymes were previously thought to be several metalloproteins with unknown function (for example, CuZnSOD was known as erythrocuprein).[2] Several common forms of SOD exist: they are proteins cofactored with copper and zinc, or manganese, iron, or nickel. For example, Brewer (1967) identified a protein that became known as superoxide dismutase as an indophenol oxidase by protein analysis of starch gels using the phenazine-tetrazolium technique.[3]

There are three major families of superoxide dismutase, depending on the metal cofactor: Cu/Zn (which binds both copper and zinc), Fe and Mn types (which bind either iron or manganese), and the Ni type, which binds nickel.

Full article ▸

related documents
Butanol
Talc
Peptide nucleic acid
Acridine
S-block
Ostwald process
Ammonium
Calcium oxide
Chymotrypsin
Quaternary structure
Electrochemical cell
Cryostasis (clathrate hydrates)
Proton pump
Biodegradation
Piperidine
Hydrophobe
Feldspar
Spinel
Myoglobin
Sodium cyanide
Haematoxylin
Asparagine
Primary nutritional groups
Reverse transcriptase
Cysteine
Hemocyanin
Lysosome
Colloid
Exon
Acetonitrile