Oxidative stress

Question 1

What is oxidative stress

Answer 1

Unbalance between anti-oxidants and radicle

Question 2

What is ROS

Answer 2

Reactive oxygen species

Question 3

Eg of ROS

Answer 3

O2, Os radicles, H2O2, OH

Question 4

Sources of ROS (endogenous)

Answer 4

• NADPH oxidase -> creates O2 radicals in the phagosomes
• xanthine oxidase -> hydrogen peroxide
• cyp450 enzymes -> oxygen radicle SER
• electron transport chain -> oxygen radicals

Question 5

Sources of ROS (environmental)

Answer 5

• pm2.5
• uv light -> singlet oxygen
• metal ions eg. Iron (fentum chem)
  and chromium (oxidation number)

Question 6

Types of redox regulation

Answer 6

• yap1p (yeast)
• nf-kb (cytoplasm)
• hif-1a
• nrf2/keap1 (modified into AO)

Question 7

Enzymatic antioxidants works by

Answer 7

Converting oxidised metabolic products -> hydrogen peroxide -> water

Question 8

Non-enzymatic antioxidants works by

Answer 8

Intercept and remove radicals

Question 9

Types of SODs

Answer 9

Cu/zn
Mn and Fe
Ni sods

Question 10

Vitamin c does what

Answer 10

A water soluble radical scavenger

Question 11

Vitamin E does what

Answer 11

A fat soluble radical scavenger

Question 12

Too much beta-carotene ?

Answer 12

Increase risk of lung cancer

Question 13

Too much vitamin E?

Answer 13

Increase risk of hemorrhagic stroke, prostate cancer, etc

Question 14

Redox regulation in bacteria

Answer 14

Via oxy R

Question 15

what are SODs

Answer 15

enzymes that are present in the presence of oxygen

Question 16

whats a radical

Answer 16

an unpaired electron

Question 17

formation of ROS

Answer 17

oxygen → superoxide (gain a single electron) → hydrogen peroxide (can undergo Fenton chemistry with Fe2+) → hydroxyl radical (can modify redox-sensitive cysteine residues)

Question 18

whats fenton chem

Answer 18

fenton chemistry = Fe3+ degrades hydrogen peroxide -> hydroxyl radicals

Question 19

ROS damages

Answer 19

→ oxidation of amino aids in proteins

→ DNA cross links (oxidation of DNA bases)

→ ROS change to Fe-S proteins (specific to respiratory)

→ lipid peroxide

Question 20

ROS damage in dna?

Answer 20

8-oxo-guanine

Question 21

can ROS be a switch for redox

Answer 21

yes

Question 22

what are SODs

Answer 22

superoxide dismutates

Question 23

name eg of antioxidants

Answer 23

SODs, catalases, NADPH, glutathione

Question 24

name some non-enzymatic antioxidants

Answer 24

vitamin C, E, selenium, carotenoid, flavonoids