Table 5 Origin, enzymatic pathways of reactive oxygen species, and their oxidized products.
[Origin and Location] Enzymatic Pathways: | [ROS] Potent Oxidants: | [Products] Oxidized lipids and proteins: |
|---|---|---|
Mitochondrial Respiratory Chain | O2• -OH• | Oxidized lipids, proteins, nucleic acids, and autoxidation byproducts |
Inflammatory Macrophage Membranous NAD(P)H Oxidase | O2• -OH• H2O2 | Advanced lipoxidation endproducts (ALE) ortho o-tyrosine meta m-tyrosine |
Granular Myeloperoxidase (MPO) | Hypochlorous acid HOCL Tyr (Tyrosine) NO2 | 3-Chlorotyrosine di-Tyrosine NO2-(Nitrotyrosine) |
Macrophage | Â | Â |
Nitric Oxide Synthase (iNOS) Inducible (iNOS) Large bursts – uncontrolled | ONOO• | NO2-(Nitrotyrosine) |
Endothelial Cell | Â | Â |
Nitric Oxide Synthase (NOS) Constitutive (cNOS) eNOS → NO nNOS → NO Small bursts – controlled | NO + O 2 • → ONOO• ONOO• | NO2-(Nitrotyrosine) NO2-(Nitrotyrosine) |
eNOS-derived NO | NO The GOOD * | Natural-occurring, local-occurring, chain-breaking, antioxidant |
Superoxide | O 2 • The BAD * | Toxic effects of ROS on proteins, lipid, nucleic acids |
Peroxynitrite | ONOO• The UGLY * | Toxic effects of ROS on proteins, lipid, nucleic acids |
Hypochlorous acid | HCLO The UGLY * | Toxic effects of ROS on proteins, lipid, nucleic acids |
Restoration of eNO Via the eNOS reaction | Antioxidant Antioxidant | Prevention of the toxic effects of ROS |