Oxidative stress Flashcards
What is oxidative stress
Unbalance between anti-oxidants and radicle
What is ROS
Reactive oxygen species
Eg of ROS
O2, Os radicles, H2O2, OH
Sources of ROS (endogenous)
- NADPH oxidase -> creates O2 radicals in the phagosomes
- xanthine oxidase -> hydrogen peroxide
- cyp450 enzymes -> oxygen radicle SER
- electron transport chain -> oxygen radicals
Sources of ROS (environmental)
- pm2.5
- uv light -> singlet oxygen
- metal ions eg. Iron (fentum chem)
and chromium (oxidation number)
Types of redox regulation
- yap1p (yeast)
- nf-kb (cytoplasm)
- hif-1a
- nrf2/keap1 (modified into AO)
Enzymatic antioxidants works by
Converting oxidised metabolic products -> hydrogen peroxide -> water
Non-enzymatic antioxidants works by
Intercept and remove radicals
Types of SODs
Cu/zn
Mn and Fe
Ni sods
Vitamin c does what
A water soluble radical scavenger
Vitamin E does what
A fat soluble radical scavenger
Too much beta-carotene ?
Increase risk of lung cancer
Too much vitamin E?
Increase risk of hemorrhagic stroke, prostate cancer, etc
Redox regulation in bacteria
Via oxy R
what are SODs
enzymes that are present in the presence of oxygen
whats a radical
an unpaired electron
formation of ROS
oxygen → superoxide (gain a single electron) → hydrogen peroxide (can undergo Fenton chemistry with Fe2+) → hydroxyl radical (can modify redox-sensitive cysteine residues)
whats fenton chem
fenton chemistry = Fe3+ degrades hydrogen peroxide -> hydroxyl radicals
ROS damages
→ oxidation of amino aids in proteins
→ DNA cross links (oxidation of DNA bases)
→ ROS change to Fe-S proteins (specific to respiratory)
→ lipid peroxide
ROS damage in dna?
8-oxo-guanine
can ROS be a switch for redox
yes
what are SODs
superoxide dismutates
name eg of antioxidants
SODs, catalases, NADPH, glutathione
name some non-enzymatic antioxidants
vitamin C, E, selenium, carotenoid, flavonoids
