ROS Flashcards
Superoxide anion
1 extre electron
O2-
Peroxide
2 extra electrons
O2 2-
Hydroxyl radical
3 extra electrons, 1 H+
.OH
Hydroxyl ion
4 extra electrons
OH-
Hydrogen peroxide
1 extra electron, 2 H+
H2O2
What is the most potent ROS?
Hydroxyl radical
Hydroxyl radicals initiate reactions that form
Lipid peroxides and organic radicals
Which ROS is NOT a radical
H2O2
Superoxide is highly reactive but
Not soluble in lipids
How does superoxide generate radicals?
Reacts NONENZYMATICALLY with H2O2 in Haber-weiss reaction
Which ROS is lipid soluble
H2O2
What does H2O2 generate
Hydroxyl radicals at Fe2+ or Cu+ sites like ETC in mitochondira
What is the haber weiss reaction?
Superoxide (O2-) +Hydrogen peroxide (H2O2) = hydroxyl radical (.OH)
What is the fenton reactions
H2O2 gets close in proximity with Fu2+ or Cu+ in ETC, generates .OH hydroxyl radical and OH-
CoQ can carry
One electron and one proton OR
Two electrons and two protons
Oxidases, oxygenases, and peroxidases
Bind O2
Transfer single electrons via METAL
Free radical intermediate of oxidases, oxygenases, and peroxidases are
Released before reduction is complete
What enzyme is a source for free radicals being leaked
Cytochrome P450
What generates H2O2
Monoamine oxidase
Peroxisomal fatty acid oxidase
Ionization radiation can split
Water into .OH (hydroxyl radical) and H. (Hydrogen radical)
What initiates lipid peroxidation
Superoxide and hydroxyl
What does lipid peroxidation do
Makes lipids in membrane permeable, things can leak through
Increase in permeability causes
Influx of Ca2+ which damages mitochondria
Cellular swelling
Which AA gets oxidized and degraded
Cysteine
Order of lipid peroxidation
Hydroxyl radical __> lipid radical –> lipid peroxy radical –> Lipid peroxide
.OH–> L. –> Loo. —> LOOH
Degradation of lipid generates
Malondialdehyde
Indicates free radical damage, is a marker in blood
Chain reactions of lipid peroxidation can be terminated by
Vitamin E, tocopherol : Lipid soluble
Vitamin C, ascorbate: water soluble
How does Vitamin E and C terminate lipid peroxidation
Donates one of their own electrons to correct the missing one and make it equally shared
What happens to proteins when hydroxyl radical attack happens
It fragments and the residues cross link with other residues
What can be used to estimate oxidative damage
8-hydroxyguanine because it is a fragmented and reformed protein caused from hydroxyl radical attack
At low concentrations NO functions as
Neurotransmitter and vasodilator
At high concentrations, NO
Combines with O2 or O2- to make RNOS
RNOS is involved with
Parkinsons, rheumatoid arthritis
nNos
Neuron nitric oxide synthase
eNOS
Endothelial neuron oxide synthase
iNOS
Inducible neuron oxide synthase
What is BH4
Terahydrobiopterin cofactor for NOS
Nitrogen dioxide is a free radical is caused by
Smoke inhalation
Cigarettes
What does superoxide dismutase do
Takes a superoxide and turns it into hydrogen peroxide
The H2O2 gets catalyzed by Fe2+ to make dangerous ROS like OH. and HOCl
What does NADPH do
Oxidizes with oxygen to make ROS on purpose.
ROS is used to attack a bacteria
What uses NADPH
Macrophages and neutrophils use it to kill the bacteria
Defective superoxide dismutase causes
Lou gehrig’s Disease
Neurons stop working
What does superoxide dismutase do with two superoxides
- Oxidizes with Cu2+ center and turns into O2
- Reduces with Cu2+ center and turns into H2O2
What converts superoxides into O2 and H2O2
Cu2+
2 H2O2 goes to
2 H2O + O2
What enzyme turns the H2O2 from SOD into water and oxygen?
Catalase
What do antioxidants do
Donates one of their electrons to missing spot of free radical
Vitamin E is in
Membranes, lipid soluble
Cellular defenses against oxygen toxicity
Antioxidant defenses: donates electron to ROS
Dietary oxidants
Endogenous oxidants
Cellular compartmentation: Separates ROS from rest of cell
Metal sequestration: Metals (Fe+) bind to protein to prevent it from being used in Fenten
Repair of cellular components
What is Cu+-Zn+ increased by
an increased superoxide
Three SOD isoenzymes
Cu+-Zn2+ in cytosol
Cu+-Zn2+ in extracellular compartment
Mn2+ in mitochondria
What type of enzyme is SOD, catalase, gluathione reductase, and glutathione peroxidase
Antioxidant scavenging enzymes
Isoflavin gives protection against
Osteoporosis
Heart disease
Breast cancer
Endogenous antioxidants
Uric acid
Melatonin
What enzyme can induce parkinsons
Rotenone
What reduces dopamin release
Monoamine oxidase (MAO)
What does glutathione peroxidase do
Converts 2GSH to GSSG
Oxidizes GSH to GSSG
Converts 2H2O to 2H2O + O2
What does glutathione reductase do
Reduces GSSG to GSH
Makes NADP+ from NADPH which comes from pentose pathway
What is GSH
Glutathione (with sulfhydryl bond)
What is GSSG
Glutathione disulfide
Vitamin E does what reaction to radicals
Reduction
Vitamin C does what reaction to radicals
Reduction
What is vitamin C rich in
Citrus fruits
What is vitamin E rich in
Legumes, nuts
Catalase is found in
Peroxisomes
