Reactive Oxygen Species Flashcards
Superoxide
O2.-
Always formed in mitochondria during ETC (CoQ)
Cytosol by microsomal cytochromes P450
Peroxisomes by cytochromes P450
Superoxide dismutase
Uses two superoxides to form H2O2 and O2
Ex: Cu++, Zinc, Manganese
Deficiency leads to Amyotrophic Lateral Sclerosis (ALS)
Haber-weiss reaction
H2O2 plus superoxide and H+ to form a Hydroxyl radical, water, and O2
Fenton Reaction
H2O2 plus Fe++ to form a hydroxyl radical and OH- and Fe+++
Hydroxyl radical
Formed by the haber-wess reaction or fenton reaction in the presence of excess H2O2.
Can also form from ionizing radiation
Most reactive and detrimental ROS
Catalase
found mainly in peroxisomes. It contains heme and can use two hydrogen peroxides as substrates at the same time to form 2 H2O and an O2
Glutathione Peroxidase
uses reduced glutathione and selenium to break H2O2 down to H2O
Can also reverse lipid peroxidation
Nonenzymatic radical scavengers
Uric Acid, Bilirubin, Melatonin
Amyotrophic Lateral Sclerosis
ALS or Lou Gehrig’s Disease
Deadly degenerative disease of the nerve cells in the brain and spinal cord that control voluntary muscle movement
Difficulty breathing, vocal cord dysfunction
Head drop due to weakness of the neck muscles
Muscle weakness, twitching, atrophy, dysphagia, hyperreflexia
Onset mostly after 40-50 years of age
NADPH Oxidase
Uses NADPH and O2 to form superoxide in neurophil cell action against bacteria
Myeloperoxidase
Uses hydrogen peroxide and chloride ions and
forms hypochlorous acid to destroy bacteria and fungi in the body
Deficiency results in recurrent severe fungal infections with candida albicans
Inducible nitric oxide synthase
uses NADPH and arginine to form nitric oxide and citrulline
When combined with O2- NO forms peroxynitrite that ultimately forms the radical nitrogen dioxide
Bridges-Good syndrome
Chronic Granulomatous Disease (CGD)
Deficiency in NADPH oxidase
Less ROS and RNOS and HOCL
Symptoms of recurrent severe bacterial and fungal infections
