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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
glycerophosphate shuttle
* 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
glyoxylate cycle
* 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
what enzyme is unaffected by ATP?
a-ketoglutarate dehydrogenase
28
What does Demerol do in ETC?
inhibits Complex 1, blocking entry of electrons being delivered by NADH
29
what does CoA cofactor do?
* nucleophilic attack to construct a high energy thioester bond * used by dihydrolipoyl transacetylase
30
what enzyme catalyzes a hydration across a double bond?
fumarase
31
what enzyme uses Fe-S cluster?
aconitase
32
if NADH levels are high, how are electrons being exported?
exported from mitochondria in the form of malate
33
what is the only water-soluble electron carrier?
cytochrome c travels through intermembrane space
34
complex 2
* succinate dehydrogenase
35
respirasomes
* multimeric supercomplexes with increased efficiency * Complex 4 ensures proper assembly of complex 1
36
between matrix and IMM, which is more negative?
matrix: generate of citrate (-) and ATP (-)
37
malate-aspartate shuttle
* uses malate to carry e- * efficient * liver, kidney, heart, takes longer but no cost * 32 ATP
38
Translocase citrate carrier
mitochondria --> cytosol Acetyl Co-A --> citrate --> Acetyl-CoA used when Acetyl-CoA builds up and have high [ATP}
39
oligomycin
* blocks movement of H+ through the F0 * blocks to surface of C10 ring, making contact with 2 neighboring molecules --> inhibits a-subunit
40
uncouplers
* 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) ## Footnote 2,4-DNP, Dicumarol, FCCP
41
dinitrophenol
generate heat in every cell --> proteins unfold and won't function uncoupling protein: UCP1
42
Complex 1 inhibitors
1. Rotenone- inhibit cellular resp in mitochondria; toxic to fish 2. Amytal- barbiturates; depressants; sedative; hypnotic 3. Demerol- opioid analgesics; narcotic; morphine | pain meds ## Footnote block O2 consumed --> slowe e- path ETC --> lower rate of breathing
43
Complex 4 inhibitors
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
Antioxidant mechanisms
1. **Superoxide dismutase** (mito: Mn+; Cytosol: Cu+, Zn+) 2. **Glutathione peroxidase** (GSH) (reductase RBC) 3. **Catalase** : fast Kcat turnover; heme protein; makes water
45
what makes up the F1 region in ATP synthase?
5 polypeptide chains: * alpha * beta * gamma * epsilon * delta
46
what are the rotating components of ATP synthase?
* C subunit * gamme * epsilon
47
where are the F0 and F1 connected?
1. gamma-episol stalk 2. 1a-subunit, 2B-subunit, delta
48
what amino acid is found in c-subunit in ATP synthase?
* Aspartate-61 * negative charge (can easily pick up protons)

biochem 410 and 411 (4 decks)

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