Oxygen Toxicity and Free Radicals Flashcards
Protection against ROS and RNOS includes enzymes. Name some enzymes.
Superoxide Dismutase (SOD)
Catalase
Glutathione Peroxidase
Glutathione Reductase
The addition of one electron in oxygen generates?
superoxide O2-
The addition of a second electron in O2- generates?
H2O2
The addition of a third electron in H2O2 generates water and?
Hydroxyl radical
Addition of electron in OH radical makes?
water molecule
___________ is the most potent ROS
Hydroxyl radical
Chain reactions initiated by ___________ lead to
the formation of lipid peroxides and organic radicals
Hydroxyl radicals
The range of action of ____________ is limited by its reduced solubility
Superoxide
Hydrogen peroxide is not a radical, but easily generates hydroxyl radicals through interactions
with ____________.
transition metals (like Fe++, Cu+)
Superoxide reacts with NO to make ___________
Peroxynitrite
____________ (Coenzyme Q/Coenzyme A) generates superoxide as a by-product of the electron transport chain
Coenzyme Q
Most _____________ bind oxygen and transfer single electrons to oxygen via a metal cofactor
oxidases (NADPH oxidase)
_______________ enzymes attempt to detoxify xenobiotics by solubilizing them through
oxidation reactions
Cytochrome P450
Induction of cytochrome P450 enzymes by __________ leads to an increased generation of free radicals, and cellular injury
Alcohol, Drug or toxin
Ionizing radiation has sufficient energy that the radiation can split water into __________ and
hydrogen radicals
hydroxyl
Amino acids proline, histidine, arginine, cysteine, and methionine are susceptible to ___________-mediated attack and oxidative damage.
hydroxyl
Age-related macular degeneration is a leading cause of blindness. What is the role of free radicals here?
Oxidative damage to the retinal pigment epithelium.
NO can exert direct toxic effects by combining with ____________________ that also
have single electrons.
iron containing compounds
_______________ enzyme produces nitric oxide (NO)
Nitric Oxide synthase
Examples of RNOS include
NO peroxynitrite peroxynitrous acid nitrogen dioxide (NO2) Nitronium ion
RNOS can lead to __________ damage and loss of its activity.
protein
____________ are given for angina because it will decompose to form NO, a potent vasodilator. This will increase blood flow to the heart, and reduce the pain.
Nitroglycerin pills
____________ is also used as a second messenger
Nitric oxide
In response to infectious agents and other stimuli, phagocytic cells of the immune system exhibit a rapid consumption of oxygen termed the ____________.
Respiratory burst
The _______________ generates ROS, hypochlorous acid (HOCl), and RNOS in order to destroy
the phagocytosed materials
respiratory burst
______________ catalyzes the formation of superoxide from oxygen and NADPH
NADPH oxidase
___________ generates hypochlorous acid (HOCl) from H2O2, which is a powerful oxidant and destroys the contents of the phagosome.
Myeloperoxidase
Chronic granulomatosis disease can result from genetic defects in _______________
NADPH oxidase
In chronic granulomatosis disease, the patient exhibits enhanced susceptibility to bacterial and fungal infections because superoxide production during the respiratory burst is ___________ (increased/decreased)
decreased
In ______________ disease, there is a dysregulation of normal inflammatory responses.
chronic granulomatosis disease
__________ produces hydrogen peroxide and oxygen from two molecules of superoxide.
Superoxide dismutase
SOD is located in _____________
mitochondria
In familial ALS, defect in ________ is there which leads to oxidative damage leading to muscle failure
SOD
___________ converts two molecules of hydrogen peroxide into two molecules of water and molecular oxygen.
Catalase
Catalase is present in _____________ (organelle)
peroxisome
The enzyme glutathione peroxidase requires ___________ metal
selenium
Nonenzymatic antioxidants examples
Vitamin C
Vitamin E
Carotenoids
Flavonoid
______________ is produced by the electron transport chain
Superoxide
____________ cannot diffuse far from the site of origin
SUperoxide
______________ can diffuse into and through cell membranes.
H2O2
Hydroxyl radicals are produced from H2O2 in the _________ reaction in the presence of Fe2+ or Cu+
Fenton
____________ is produced in neutrophils during the respiratory burst to destroy invading organisms
Hypochlorus acid (HOCl)
The Attacking species in HOCl is _______
OCl-
____________ decays so fast that it is probably not a significant in vivo source of toxicity
Singlet oxygen
____________ is oxygen with antiparallel spins
Singlet oxygen
___________ is produced at high oxygen tensions from absorption of UV light
Singlet oxygen
Peroxynitrite can generate ______________
Nitrogen dioxide
Which of the following is not a radical?
a. OH*
b. LOO*
c. NO2
d. ONOO-
e. NO
ONOO-
