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biochem 410 and 411 > 411: exam 2 > Flashcards

411: exam 2 Flashcards

1
Q

oxidative phosphorylation

A

proton gradient drives synthesis of ATP

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2
Q

why does entry point for electrons from NADH differ from those of FADH2?

A

reduction potentials (difference in electron transfer between 2 species)

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3
Q

what is E°’ ?

A

standard reduction potential
electorn affinity measured in volts
measured relative to H2 electrode at pH 0
H2 gas –> 2e- +2H+

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4
Q

how many protons does each complex pump out?

A

1: 4H+
2: 0
3: 4H+
4: 2H+

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5
Q

where does e- exchange happen in FAD?

A

isoalloxazin in riboflavin

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6
Q

what vitamin is Thiamine?

A

Vitamin B

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7
Q

how is lipoic acid acquired?

A

fatty acid precursor in animals

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8
Q

how is Coenzyme A acquired?

A
  • Vitamin B5
  • almost all food are a source of it
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9
Q

how is FAD/FMN acquired?

A
  • vitain B2 (riboflavin)
  • eggs, organ meats, lean meats, grain
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10
Q

how is NAD+ acquired?

A
  • vitamin B3
  • synthesized from tryptophan
  • LIVER, tuna, salmon
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11
Q

lipoic acid

A
  • bound to lysyl residue to form lipoamide
  • serves as a swining arm to transfer intermediates from E1, E2, E3
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12
Q

why are arsenic compounds toxic?

A

because they bind to sulfyhydryl compounds when in contact with lipoamide and dihydrolipoamide

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13
Q

what halts respiration?

A

inactivation of lipoamide with pyruvate dehydronease and a-ketoglutarate dehydrogenase

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14
Q

what does TPP do?

A
  • stabilizes resonance of carbanion
  • facilitates decarboxylation of pyruvate
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15
Q

which arm does aconitase remove?

A

pro-R arm

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16
Q

what dictates PDH and thus PDHC activity?

A

covalent modification of Ser residue
(phosphorylation and dephosphorylation of E1)

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17
Q

what activates and inhibits PDHK?

A

activates: NADH, Acetyl-CoA
inhibits: pyruvate

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18
Q

what activates and inhibits PDHP?

A

activates: Ca2+, insulin
inhibits: Acetyl CoA, ATP, NADH

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19
Q

what activates and inhibits PDHC?

A

activates: AMP, CoA, NAD+, Ca2+,
inhibits: ATP, acetyl-CoA, NADH, fatty acids

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20
Q

cataplerotic rxns definition and those in TCA cycle

A
  • decrease concentration of TCA intermediates
  • citrate –> fatty acids, cholesterol
  • a-Ketogluterate –> glutamate –> purine nt (Arg and Pro)
  • succinyl-CoA –> porphyrins
  • oxaloacetate –> malate –> glucose
  • oxaloacetate –> amino acids
21
Q

anaplerotic rxns definition and those in TCA cycle

A
  • increase [TCA intermediate]
  • amino acids –> a-ketogluterate
  • odd-chain fatty acids and Ile,Met,Val –> succinyl CoA
  • Asp, Phe, Tyr –> fumarate
  • amino acids and pyruvate –> oxaloacetate

increase TCA intermediates

22
Q

what are the 3 anaplerotic enzymes and what do they convert?

A

PEP carboxylase: PEP –> oxaloacetate
pyruvate carboxylase: pyruvate –> oxaloacetate
malic enzyme: pyruvate –> malate

23
Q

what does malate dehydrogenase do and where is it found?

A
  • cytosol and matrix
  • reduces OAA to malate to be transported to cytosol and then oxidized back to OAA (across IMM)
  • because NADH cant cross IMM
24
Q

Malate-Aspartate Shuttle routes

A
  1. aspartate aminotransferase- does NOT requires NAD/NADH
  2. malate dehydrogenase- requres NAD/NADH (reduces equivalents that can be transported across IMM)

liver has a variation of route 1 that uses Aspartate for a deamination reaction via urea cycle before conversion to OAA

25
Q

glycerophosphate shuttle

A
  • electrons from NADH –>DHAP–> G3P –> FAD –> Q via 3-phosphoglycerol dehydrogenase
  • makes 1.5 ATP instead of 2.5 (30 total)
  • rengenerates NAD+
  • skeltal muslces and brain
26
Q

glyoxylate cycle

A
  • plants cant do enough photosynthesis –> rely on acetate as carbon source
  • allows for OAA –> acetyl CoA –> glucose
  • CO2-evolving steps are bypassed and an extra acetate is used
  • isocitrate lyase and malate synthase keep 2C -> make glucose –> survive
27
Q

what enzyme is unaffected by ATP?

A

a-ketoglutarate dehydrogenase

28
Q

What does Demerol do in ETC?

A

inhibits Complex 1, blocking entry of electrons being delivered by NADH

29
Q

what does CoA cofactor do?

A
  • nucleophilic attack to construct a high energy thioester bond
  • used by dihydrolipoyl transacetylase
30
Q

what enzyme catalyzes a hydration across a double bond?

A

fumarase

31
Q

what enzyme uses Fe-S cluster?

A

aconitase

32
Q

if NADH levels are high, how are electrons being exported?

A

exported from mitochondria in the form of malate

33
Q

what is the only water-soluble electron carrier?

A

cytochrome c
travels through intermembrane space

34
Q

complex 2

A
  • succinate dehydrogenase
35
Q

respirasomes

A
  • multimeric supercomplexes with increased efficiency
  • Complex 4 ensures proper assembly of complex 1
36
Q

between matrix and IMM, which is more negative?

A

matrix: generate of citrate (-) and ATP (-)

37
Q

malate-aspartate shuttle

A
  • uses malate to carry e-
  • efficient
  • liver, kidney, heart, takes longer but no cost
  • 32 ATP
38
Q

Translocase citrate carrier

A

mitochondria –> cytosol
Acetyl Co-A –> citrate –> Acetyl-CoA
used when Acetyl-CoA builds up and have high [ATP}

39
Q

oligomycin

A
  • blocks movement of H+ through the F0
  • blocks to surface of C10 ring, making contact with 2 neighboring molecules –> inhibits a-subunit
40
Q

uncouplers

A
  • disrupt tight coupling between e- transport and ATP synthase
  • obtain H+ in IMM –> matrix –> bypass ATP synthase as H+ pump –> e- released as heat instead of ATP
  • only expressed in specific tissue (brown adipose)

2,4-DNP, Dicumarol, FCCP

41
Q

dinitrophenol

A

generate heat in every cell –> proteins unfold and won’t function
uncoupling protein: UCP1

42
Q

Complex 1 inhibitors

A
  1. Rotenone- inhibit cellular resp in mitochondria; toxic to fish
  2. Amytal- barbiturates; depressants; sedative; hypnotic
  3. Demerol- opioid analgesics; narcotic; morphine

pain meds

block O2 consumed –> slowe e- path ETC –> lower rate of breathing

43
Q

Complex 4 inhibitors

A

bind to heme of cytochrome a and lock them up so don’t move
1. cyanide- oxygen can’t get into complex 4 –> stay in Hb in blood
2. Azide
3. Carbon Monoxide

44
Q

Antioxidant mechanisms

A
  1. Superoxide dismutase (mito: Mn+; Cytosol: Cu+, Zn+)
  2. Glutathione peroxidase (GSH) (reductase RBC)
  3. Catalase : fast Kcat turnover; heme protein; makes water
45
Q

what makes up the F1 region in ATP synthase?

A

5 polypeptide chains:
* alpha
* beta
* gamma
* epsilon
* delta

46
Q

what are the rotating components of ATP synthase?

A
  • C subunit
  • gamme
  • epsilon
47
Q

where are the F0 and F1 connected?

A
  1. gamma-episol stalk
  2. 1a-subunit, 2B-subunit, delta
48
Q

what amino acid is found in c-subunit in ATP synthase?

A
  • Aspartate-61
  • negative charge (can easily pick up protons)

biochem 410 and 411 (4 decks)

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