Superoxide Dismutase

About SOD / Superoxide Dismutase:

Superoxide Dismutase is the enzyme responsible for converting the superoxide anion (O−2) into either ordinary molecular oxygen (O2) or hydrogen peroxide (H2O2). It thus directly protects against oxidative damage.
Mutations in SOD (more specifically SOD1) are strongly linked with familial amyotrophic lateral sclerosis (ALS). It is also believed to be linked with sporadic ALS. Inactivation of SOD (again, specifically SOD1) is strongly linked with hepatocellular carcinoma.

SOD Function
SOD is the body’s main defense against oxidative damage. Oxidative damage has been linked with a number of conditions ranging including diabetes mellitus, hypertension, ischemic diseases, and malignancies.
SOD is complemented by other enzymes notably catalase. These break down the hydrogen peroxide (H2O2) produced by SOD. Although hydrogen peroxide (H2O2) is less toxic than the superoxide anion (O−2), it still has the potential to be damaging if left untreated.

Superoxide Dismutase Structure
In humans, SOD exists in three forms. The main form is cytoplasm (SOD1). It also exists in mitochondria (SOD2)) and extracellular (SOD3). SOD1 comprises two units and contains copper and zinc. SOD2 comprises four units and contains manganese. SOD3 has four units and contains copper and zinc.

SOD Interaction
SOD1, SOD2, and SOD3 interact with each other and with the following proteins:
GPX7
GPX3
GPX6
GPX2
PRDX2
GSR
PRDX1
GPX5
TXNRD1
CAT
TXN
MSRZ
GPX1
GPX8
TP53
TXNIP
FOXO3
MAP3K5

Superoxide Dismutase Mechanism of action
SOD1 uses a cyclical dismutation reaction to detoxify the superoxide (O−2) radical. Firstly, O2- is oxidized to O2 while Cu2+ is reduced to Cu1+. Secondly, O2 is reduced to H2O2, and Cu1+ is oxidized to Cu2+. The cycle then begins again.