Reactive Oxygen Species (ROS) Flashcards
A …… is a molecule that has a single unpaired electron in an orbital and is highly reactive that is scavenged by antioxidants
Free Radical
………… include free radicals and compounds leading to free radicals.
Reactive Oxygen Species
Superoxide, hydroxyl radical, nitric oxide, nitrogen dioxide are…..
Free Radicals
Hydrogen peroxide and peroxynitrite
are….
Species leading to free radicals
ROS and RNOS are formed during ……. and need to be scavenged in order to prevent ……… related to DNA, lipids and proteins.
Oxidative stress
cell damage
ROS formation is increased by:
- High oxygen tension (Example COPD patients on supplement oxygen).
- Hypoxia, carbon monoxide poisoning, ischemic reperfusion.
- High levels of acetaldehyde in the liver after ethanol abuse.
CoQ, a lipid component of the Electron Transport Chain (ETC), can accidentally transfer one electron to molecular oxygen. This generates……….
Superoxide
Superoxide is scavenged by………which uses two superoxides at the same time as substrates. The product is …….
Superoxide dismutase (SOD) Hydrogen peroxide.
……….. is lipid soluble and can diffuse through membranes which leads to hydroxyl radicals when it is not scavenged.
Hydrogen Peroxide
Hydroxyl radical OH. is formed from hydrogen peroxide interaction with superoxide called the……… reaction
Haber-Weiss Reaction
Hydroxyl radical OH. is formed from hydrogen peroxide interaction with ferrous iron called the……… reaction
Fenton Reaction
……….is the most detrimental ROS.
Hydroxyl radical OH.
Hydrogen peroxide is scavenged by:
Catalase or by Glutathione peroxidase
………. is found mainly in peroxisomes and degrades hydrogen peroxide when the peroxisomal hydrogen peroxide level gets too high
Catalase
…………. acts on hydrogen peroxidase needs selenium as cofactor and uses 2 molecules of reduced glutathione (GSH).
Glutathione peroxidase
If the peroxidized fatty acids are not repaired by……….. then they will be shortened to smaller segments resulting in “leaking” of membranes.
Glutathione peroxidase
…………. more susceptible to ROS damage than nuclear DNA as it does not have histones and it is close to the ETC
Mitochondrial DNA
A crushing injury leads to the formations of …….. in the Fenton reaction due to loss of sequestration of iron.
Hydroxyl Radicals
Enzymatic radical scavengers:
Superoxide dismutase (SOD)
Catalase
Glutathione peroxidase
Nonenzymatic endogenous radical scavengers:
▪ Uric acid (High levels can lead to gout)
▪ Glutathione (Released by the liver into the blood)
▪ Bilirubin (High levels can lead to jaundice)
Dietary radical scavengers:
vitamins C and E, carotenoids, flavonoids, phytochemicals, polyphenols, isoprenoids and PUFA
…… is a deadly degenerate disease of upper and lower motor neurons that control voluntary muscle movement
Amyotrophic Lateral Sclerosis (ALS)
ALS is caused by a deficiency of …….
Superoxide dismutase (SOD)
Symptoms of ALS:
Symptoms:
- Difficulty breathing, vocal cord dysfunction.
- Head drop due to weakness of the neck muscles.
- Muscle weakness, twitching, atrophy, dysphagia, hyper-reflexia.
Neutrophils uses NADPH oxidase to synthesize…..
Superoxide
…… forms hypochlorous acid which destroys bacteria and fungi
Myeloperoxidase
…………..formed in macrophages by ………… is needed for RNOS formation as cell defense
Nitric Oxide (NO) Inducible NO synthase (iNOS)
Functions of nitric oxide:
- Relaxes smooth muscle and leads to vasodilation.
- Prevents platelet aggregations.
- Functions as neurotransmitter in brain.
- Destruction of invading bacteria.
Disease: Hereditary (X-linked) NADPH oxidase deficiency that results in Recurrent severe infections by bacteria (pneumonia) or fungi (aspergillus)
Chronic Granulomatous Disease (CGD)
Disease: Recurrent severe infections by candida albicans caused by decreased formation of HOCL (bleach). Resulting in Oral and Genital Infections and systemic Infections
Myeloperoxidase Deficiency
