1. BIOLOGICAL ROLE OF OXYGEN
Carbohydrate metabolism for ATP Production (Mitochondria)
Degradation of metabolic by-products by (Peroxisomes)

2. CELLULAR RESPIRATION
Production of Reactive Oxygen Species

3. REACTIVE OXYGEN SPECIES (ROS)
NADPH + O2
NADPH oxidase
Superoxide (O2-.)
Superoxide dismutase
Hydrogen peroxide (H2O2)
Myeloperoxidase
Hypochlorite (HOCl)
Fe2+
Catalase
Hydroxyl radical (OH.)
O2 + H2O

4. GENERATION OF REACTIVE OXYGEN SPECIES

5. GENERATION OF ROS AS METABOLIC BY-PRODUCTS

6. GENERATION OF ROS IN IMMUNE DEFENSES

7. OXIDATIVE DAMAGES

8. OXIDATIVE DAMAGE TO LIPIDS
Increase membrane rigidity
Reduce activity of membrane-bound enzyme
Alter activity of membrane receptors
Alter cell permeability

9. OXIDATIVE DAMAGE TO PROTEINS
Site-specific amino acid modifications
Fragmentation of peptide chain
Aggregation of cross-linked reaction products
Increased susceptibility to proteolysis
Degradation of enzymes

10. OXIDATIVE DAMAGE TO NUCLEIC ACIDS
Mutation
Single strand breakage
Nucleotide degradation
Cross-linking to protein

11. ANTIOXIDANTS Enzymatic Antioxidants Non-Enzymatic Antioxidants
Superoxide dismutase
Catalysis the dismutation of superoxide to hydrogen peroxide.
Catalase
Catalysis the dismutation of superoxide to water and oxygen.
Glutathione peroxidase
Degradation of hydrogen peroxide
Non-Enzymatic Antioxidants
Vitamin E
Trap peroxy radicals in cellular membranes.
Vitamin C
Reduce radicals from a variety of sources.
Recycling of Vitamin E radicals.
Glutathione
Defense against reactive oxygen species.