Antioxidant / Oxidant Balance:

• ANTIOXIDANTS
  • Overview
  • Enzymatic Antioxidants
  • Non-Enzymatic Antioxidants
• AOX  ^  ROS
• OXIDANTS
  • Meet Dr ROS Jeckyll and Mr ROS Hyde
  • Dr. ROS Jeckyll
  • Mr. ROS Hyde
  • ROS Chart
  • Where do ROS come from in the body?

(1) Enzymatic Antioxidants

(Biochemical enzyme catalysts, found in organisms' healthy cells)

Superoxide Dismutase (SOD) - this water-soluble enzyme needs Manganese, Zinc, Copper (marginal to deficient in US diet), depending on location (Zinc-Copper SOD in the cytosol, Manganese SOD in the mitochondria.

•  Removes the Superoxide Radical(source ofH₂O₂ and OH^•).   By catalyzing the dismutation of O₂^•- into oxygen and hydrogen peroxide

•  Concentration of SOD in mammals is directly proportional to their life span

•  Found in the cells' cytoplasm and mitochondria (energy factory)

Catalase (CAT) - found in membranes of eukaryotic cells (thus not in bacteria); Requires Iron to function

•  Catalyze decomposition of Hydrogen Peroxide (H₂O₂ ) to oxygen and water

•  Highly reactive enzyme found in peroxisomes (cellular organelles containing enzymes)

Glutathione Peroxidase (GPx).    Contains and Requires Selenium to function; actually a family of 8 isoforms: Gpx1 (in cytoplasm ofmost all mammalian cells), GPx2 (intestines) GPx3 thru GPx8, each found in specific areas of the body)

-   Two main functions (in reactions requiring glutathione (GSH)):

•  Catalyze reduction of lipid hydroperoxides (ROOH) to their corresponding alcohols

•  Catalyze reduction of free Hydrogen Peroxide (H₂O₂) (source of hydroxyl radicals) to water - H₂O₂ is the preferred substrate of GPx1