Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
BIOLOGICAL ROLE OF OXYGEN • Carbohydrate metabolism for ATP Production (Mitochondria) • Degradation of metabolic by-products by (Peroxisomes) CELLULAR RESPIRATION Production of Reactive Oxygen Species REACTIVE OXYGEN SPECIES (ROS) NADPH + O2 NADPH oxidase Superoxide (O2-.) Superoxide dismutase Hydrogen peroxide (H2O2) Hypochlorite (HOCl) Hydroxyl radical (OH.) O2 + H2O Catalase Fe2+ Myeloperoxidase GENERATION OF REACTIVE OXYGEN SPECIES GENERATION OF ROS AS METABOLIC BY-PRODUCTS GENERATION OF ROS IN IMMUNE DEFENSES OXIDATIVE DAMAGES OXIDATIVE DAMAGE TO LIPIDS • Increase membrane rigidity • Reduce activity of membrane-bound enzyme • Alter activity of membrane receptors • Alter cell permeability 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 OXIDATIVE DAMAGE TO NUCLEIC ACIDS • Mutation • Single strand breakage • Nucleotide degradation • Cross-linking to protein ANTIOXIDANTS 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.