Reactive Oxygen Species - RR

Question 1

are ROS incompletely oxidized or incompletely reduced oxygen species?

Answer 1

incompletely reduced. those containing unpaired electrons are referred to as free radicals

Question 2

what is the primary ROS

Answer 2

superoxide, O2 + 1e-

Question 3

what is the secondary ROS

Answer 3

hydroxyl radical, OH + 1e-

Question 4

is superoxide an oxidant? t/f

is it a free radical? t/f

Answer 4

it is both an oxidant, as it oxidizes stuff around it, and a free radical, as it has an unpaired electron

Question 5

how is superoxide produced

Answer 5

mitochondria make it as a product of ATP synthesis when an extra electron sneaks into the complexes in ETS and is delivered to O2

Question 6

is hydrogen peroxide an oxidant? a free radical?

Answer 6

it IS an oxidant, it is NOT a free radical

Question 7

what conditions increase the production of superoxide

Answer 7

High NADH/NAD+ ratio from over reduction of ETS
Electron Transport System damage
Hypoxia
Xenobiotics - some block electron transport ie MPTP or rotenone

Question 8

what are non-mitochondrial sources for ROS

Answer 8

NOX - NADPH Oxidase - usually found in phagocytes

Xanthine Oxidase and Monoamine Oxidase (XO, MAO)

Question 9

what is the normal function of XO

Answer 9

catalyzes purine catabolism

Question 10

what is the normal function of MAO

Answer 10

dopamine catabolism

Question 11

Whats the Fenton Reaction

Answer 11

transfers an electron to H2O2 from free metal ions to convert superoxide and hydrogen peroxide to hydroxyl radical and water

Question 12

what is the catalyst in the Fenton Reaction

Answer 12

Iron

Question 13

What is the primary RNOS

Answer 13

NO + 1e-, generated by nitric acid synthase

Question 14

what happens when NO. reacts with O2.

Answer 14

it can form peroxynitrate (ONOO-) a very reactive oxidant

Question 15

What does 8-hydroxy-2’-deoxyguanosine do?

Answer 15

indicator of extent of DNA Damage in the cell

Question 16

What do 4-hydroxy-2E-nonenal and malondialdehyde tell you?

Answer 16

biomarkers of lipid peroxidation

Question 17

how many stages does a radical chain reaction have and what are they

Answer 17

3. initiation, propagation and termination

Question 18

which lipids are the most prone to lipid oxidation

Answer 18

PUFAs like arachidonic acid and linoleic acid bc the hydrogens close to the double bond are extremely reactive and prone to losing an electron

Question 19

why is DNA a favorite target of the hydroxyl radical

Answer 19

because nucleic acids bind iron really well

Question 20

what does SOD do?

Answer 20

superoxide dismutase - converts 2 molecules of superoxide to one molecule of O2 and one H2O2

Question 21

what does glutathione peroxidase do? aka catalase?

Answer 21

converts hydrogen peroxide to water, also contains Se

Question 22

what are the non-enzymatic ROS scavengers

Answer 22

Coenzyme Q10, Vitamin E, Vitamin C, Glutathione

Question 23

what is the physiological role of H2O2

Answer 23

second messenger in redox signaling, where oxidation of signaling proteins is proposed to involve sensors