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 | ||
|
Nitric Oxide Synthase (iNOS) Inducible (iNOS) Large bursts – uncontrolled | ONOO• | NO2-(Nitrotyrosine) |
| Endothelial Cell | ||
|
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 |