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Biochemistry > ROS > Flashcards

ROS Flashcards

1
Q

Superoxide anion

A

1 extre electron
O2-

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1
Q

Peroxide

A

2 extra electrons
O2 2-

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2
Q

Hydroxyl radical

A

3 extra electrons, 1 H+
.OH

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3
Q

Hydroxyl ion

A

4 extra electrons
OH-

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4
Q

Hydrogen peroxide

A

1 extra electron, 2 H+
H2O2

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5
Q

What is the most potent ROS?

A

Hydroxyl radical

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6
Q

Hydroxyl radicals initiate reactions that form

A

Lipid peroxides and organic radicals

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7
Q

Which ROS is NOT a radical

A

H2O2

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8
Q

Superoxide is highly reactive but

A

Not soluble in lipids

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9
Q

How does superoxide generate radicals?

A

Reacts NONENZYMATICALLY with H2O2 in Haber-weiss reaction

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10
Q

Which ROS is lipid soluble

A

H2O2

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11
Q

What does H2O2 generate

A

Hydroxyl radicals at Fe2+ or Cu+ sites like ETC in mitochondira

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12
Q

What is the haber weiss reaction?

A

Superoxide (O2-) +Hydrogen peroxide (H2O2) = hydroxyl radical (.OH)

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13
Q

What is the fenton reactions

A

H2O2 gets close in proximity with Fu2+ or Cu+ in ETC, generates .OH hydroxyl radical and OH-

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14
Q

CoQ can carry

A

One electron and one proton OR
Two electrons and two protons

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15
Q

Oxidases, oxygenases, and peroxidases

A

Bind O2
Transfer single electrons via METAL

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16
Q

Free radical intermediate of oxidases, oxygenases, and peroxidases are

A

Released before reduction is complete

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17
Q

What enzyme is a source for free radicals being leaked

A

Cytochrome P450

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18
Q

What generates H2O2

A

Monoamine oxidase
Peroxisomal fatty acid oxidase

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19
Q

Ionization radiation can split

A

Water into .OH (hydroxyl radical) and H. (Hydrogen radical)

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20
Q

What initiates lipid peroxidation

A

Superoxide and hydroxyl

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21
Q

What does lipid peroxidation do

A

Makes lipids in membrane permeable, things can leak through

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22
Q

Increase in permeability causes

A

Influx of Ca2+ which damages mitochondria
Cellular swelling

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23
Q

Which AA gets oxidized and degraded

A

Cysteine

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24
Q

Order of lipid peroxidation

A

Hydroxyl radical __> lipid radical –> lipid peroxy radical –> Lipid peroxide

.OH–> L. –> Loo. —> LOOH

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25
Q

Degradation of lipid generates

A

Malondialdehyde
Indicates free radical damage, is a marker in blood

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26
Q

Chain reactions of lipid peroxidation can be terminated by

A

Vitamin E, tocopherol : Lipid soluble
Vitamin C, ascorbate: water soluble

27
Q

How does Vitamin E and C terminate lipid peroxidation

A

Donates one of their own electrons to correct the missing one and make it equally shared

28
Q

What happens to proteins when hydroxyl radical attack happens

A

It fragments and the residues cross link with other residues

29
Q

What can be used to estimate oxidative damage

A

8-hydroxyguanine because it is a fragmented and reformed protein caused from hydroxyl radical attack

30
Q

At low concentrations NO functions as

A

Neurotransmitter and vasodilator

31
Q

At high concentrations, NO

A

Combines with O2 or O2- to make RNOS

32
Q

RNOS is involved with

A

Parkinsons, rheumatoid arthritis

33
Q

nNos

A

Neuron nitric oxide synthase

34
Q

eNOS

A

Endothelial neuron oxide synthase

35
Q

iNOS

A

Inducible neuron oxide synthase

36
Q

What is BH4

A

Terahydrobiopterin cofactor for NOS

37
Q

Nitrogen dioxide is a free radical is caused by

A

Smoke inhalation
Cigarettes

38
Q

What does superoxide dismutase do

A

Takes a superoxide and turns it into hydrogen peroxide
The H2O2 gets catalyzed by Fe2+ to make dangerous ROS like OH. and HOCl

39
Q

What does NADPH do

A

Oxidizes with oxygen to make ROS on purpose.
ROS is used to attack a bacteria

40
Q

What uses NADPH

A

Macrophages and neutrophils use it to kill the bacteria

41
Q

Defective superoxide dismutase causes

A

Lou gehrig’s Disease
Neurons stop working

42
Q

What does superoxide dismutase do with two superoxides

A
  1. Oxidizes with Cu2+ center and turns into O2
  2. Reduces with Cu2+ center and turns into H2O2
43
Q

What converts superoxides into O2 and H2O2

A

Cu2+

44
Q

2 H2O2 goes to

A

2 H2O + O2

45
Q

What enzyme turns the H2O2 from SOD into water and oxygen?

A

Catalase

46
Q

What do antioxidants do

A

Donates one of their electrons to missing spot of free radical

47
Q

Vitamin E is in

A

Membranes, lipid soluble

48
Q

Cellular defenses against oxygen toxicity

A

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

49
Q

What is Cu+-Zn+ increased by

A

an increased superoxide

50
Q

Three SOD isoenzymes

A

Cu+-Zn2+ in cytosol
Cu+-Zn2+ in extracellular compartment
Mn2+ in mitochondria

51
Q

What type of enzyme is SOD, catalase, gluathione reductase, and glutathione peroxidase

A

Antioxidant scavenging enzymes

52
Q

Isoflavin gives protection against

A

Osteoporosis
Heart disease
Breast cancer

53
Q

Endogenous antioxidants

A

Uric acid
Melatonin

54
Q

What enzyme can induce parkinsons

A

Rotenone

55
Q

What reduces dopamin release

A

Monoamine oxidase (MAO)

56
Q

What does glutathione peroxidase do

A

Converts 2GSH to GSSG
Oxidizes GSH to GSSG
Converts 2H2O to 2H2O + O2

57
Q

What does glutathione reductase do

A

Reduces GSSG to GSH
Makes NADP+ from NADPH which comes from pentose pathway

58
Q

What is GSH

A

Glutathione (with sulfhydryl bond)

59
Q

What is GSSG

A

Glutathione disulfide

60
Q

Vitamin E does what reaction to radicals

A

Reduction

61
Q

Vitamin C does what reaction to radicals

A

Reduction

62
Q

What is vitamin C rich in

A

Citrus fruits

63
Q

What is vitamin E rich in

A

Legumes, nuts

64
Q

Catalase is found in

A

Peroxisomes

Biochemistry (13 decks)

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