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biochemistry Jonklaas > citric acid cycle > Flashcards

citric acid cycle Flashcards

1
Q

what are the reactants and products of the TCA

A

pyruvate+ CoA + NAD+= acetyl co a + co2 + nadh

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2
Q

what vitamin does coa come from

A

b5 pantothenate

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3
Q

what bond does coA have

A

thioester high energy bond

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4
Q

wht does CoA do

A

carrier of acyl gps

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5
Q

what cofactors does PDH use

A

TPP
CoAsh
Lipoic Acid
FAD
NAD
the coons like fighting niggas

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6
Q

describe TPP location and function

A
  • catalytic
  • bound to E1
  • decarboxylates pyruv
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7
Q

describe lipoic acid and its loc and func.

A
  • catalytic
  • inked to lys on e2 (lipoamide)
  • ## accepts hydroxyethyl carbanion from tpp
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8
Q

coenzyme A

A

stochiometric
- substrate for E2
- accepts aceytl group from lipoamide

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9
Q

FAD flavin

A
  • bound to E3
  • reduced by lipoamide
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10
Q

NAD+ catalutic

A

substrate for E3
reduced by FADH@

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11
Q

Q: What metabolic enzyme does arsenite primarily inhibit?

A

inhibits pyruvate

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12
Q

what is the first enzyme of tca

A

citrate synthase
- add acetyl group to oxalocacetate to make citrate

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13
Q

why is succinyl coa synthetase important

A
  • uses SLP
  • nucleoside triphosphate is made - atp in most prok
  • gtp in euk
  • driven by hydrolysis of CoA ester
  • inolves phosphohistidine
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14
Q

succinate DH is competitively inhibited why what

A

malonate making it poison

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15
Q

what is the only enzyme bound of TCA

A

succinate DH bc its complex 2 of the ETC

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16
Q

what happens during succinate dh

A
  • hydride transfer and oxidation with fad
  • fad reduced
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17
Q

what are the characteristics of riboflavin vitamin b12

A
  • coenzyme: FAD, FMN
  • oxidation reduction
    growth retardation
18
Q

why is fumarase a bidrecrtional rxn

A
  • lyase reaction
  • prochiral differentiation= molecule that is not chiral has the potential to become chiral
19
Q

what is the product of tca in euk

A
  • 2 co2
  • 1 gtp= atp equivalent
  • 3 nadh
  • 1 fadh2
    -(4 reduced coenzues)
20
Q

how is pyruvate dh regulated

A

producut inhibition by NADH Nad+ for binding sites e3
-acetyl w/ CoA for binding site e2

21
Q

what does Pyr. DH do to enzymes E2 and E3

A
  • drive them backwards
  • keeps E2 in acetylated form unable to accept hydroxyethyl gp from E1
22
Q

how to control phosphorylation

A
  • phosphoryl of side chain OH,S,T,Y residues or imidazole= N of His
  • transfer of ATP
  • causes cascades of one kinase to another
  • amplify signals
23
Q

which enzyme is used by reversible phosphorylation of pyruvate DH

A

enzyme 1
- deacitvated by PDH kinase

24
Q

what activatdes PDH kinase

A
  • acetyl co a, nadh/Nad+, or ATP
    this leads to the deactivation
25
Q

when does PDH switch off

A

when the energy is high and biosynthetic intermediates are high

26
Q

what keeps PDH kinase active

A
  • pyruvate, ADP, Ca+2
  • low signal = make atp
27
Q

enzyme 1 is activated by what in regulation of pDH

A

-dephosphorylation PDH phophatase

28
Q

what are some main points of TCA and PDH rxn

A
  1. occurs in mito matrix except for succinate DH( membrane bound)
  2. PDH, citrate synthasae, isocitrate dh, alpha keto dh = irrreversible
  3. irreversible = regulated
29
Q

what are the main regulatory enzymes of tca

A
  • isocitrate DH
  • PDH
30
Q

which rxns are inhibited by NADH and ATP

A
  • pdh
    -citrate synthase
  • isocitate
  • alpha keto dh
31
Q

what is the enzyme that makes cycle underectional

A

alpha keto dh

32
Q

what does succinal co a synthetase use to generate atp

A

SLP

33
Q

what are the anaplerotic reactons and what is anaplerotic

A
  • replenishes intermediates
  • Pyruvate carb
    -PEP carboxy
  • malic enzyme
34
Q

what does pyruvate carb do

A
  • converts pyruvate to oxalocae
    found in liver, kidney
35
Q

what does pep carboxy do

A

converts PEP –> oxalocaetate
- higher in plants, yeast, bacteria not animals

36
Q

what does malic enzyme do

A

pyruv–> malate
widely distributed by prok and euk

37
Q

what is the role of aspartate transaminase in tca

A

facilitates the conversion of aspartate ito oxalocaetate , linking nitrogen metabolish with central carbon metabolism

38
Q

what is the first enzyme of gluconeogenesis

A

pyruvate carboxylase

39
Q

what does pyruv carbox do again

A
  • catalyzes the atp and biotin dependent conversionof pyr to oxalocatee in mitochondrial matrix
40
Q

what happens to carboxyl c of acetate

A

turns into co2 in the second turn of the cycle

41
Q
A

biochemistry Jonklaas (17 decks)

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