Superoxide dismutase
Introduction
Superoxide dismutase (SOD) is an enzyme that plays a critical role in the defense of living cells against reactive oxygen species (ROS), specifically the superoxide radical. The enzyme catalyzes the dismutation (or partitioning) of the superoxide radical into either ordinary molecular oxygen (O2) or hydrogen peroxide (H2O2). Superoxide is produced as a by-product of oxygen metabolism and, if not regulated, causes many types of cell damage.
Structure and Function
Superoxide dismutases are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide. They are an important antioxidant defense in nearly all cells exposed to oxygen. 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.
Mechanism of Action
The molecular mechanism of superoxide dismutase is to facilitate the reaction of two superoxide radicals to produce hydrogen peroxide and molecular oxygen. This reaction is extremely important in the body as a defense mechanism against reactive oxygen species, which are a byproduct of cellular respiration.
Role in Disease
Mutations in the superoxide dismutase genes can cause familial amyotrophic lateral sclerosis (ALS, a form of motor neuron disease). Some evidence also suggests that superoxide dismutase could play a role in age-related macular degeneration (AMD) and keratoconus.
Therapeutic Use
Superoxide dismutase has been used in the treatment of a variety of conditions, including radiation exposure, inflammation, and aging. However, the effectiveness of superoxide dismutase in these applications is still under investigation.