Oxidation response is stimulated by a disturbance in the balance between the production of reactive oxygen species and antioxidant responses, known as oxidative stress. Active species of oxygen naturally occur in aerobic cells and have both intracellular and extracellular sources. These species, if not controlled, damage all components of the cell, including proteins, lipids and DNA. Hence cells need to maintain a strong defense against the damage. The following table gives an idea of the antioxidant defense system in bacterial system.
Line of defense | Components | Function | Examples |
---|---|---|---|
First |
Metal chelators |
prevent free radical formation by inhibiting metal catalyzed reactions |
|
Second |
Low molecular weight compounds and antioxidant enzymes |
deactivate free radicals (ROS) before some biological molecule is damaged
|
superoxide dismutase (SOD) and catalase
|
Third
|
DNA repair systems
protein repair system lipid repair system |
repair biomolecules after they were damaged by ROS
|