citric acid cycle Flashcards
what are the reactants and products of the TCA
pyruvate+ CoA + NAD+= acetyl co a + co2 + nadh
what vitamin does coa come from
b5 pantothenate
what bond does coA have
thioester high energy bond
wht does CoA do
carrier of acyl gps
what cofactors does PDH use
TPP
CoAsh
Lipoic Acid
FAD
NAD
the coons like fighting niggas
describe TPP location and function
- catalytic
- bound to E1
- decarboxylates pyruv
describe lipoic acid and its loc and func.
- catalytic
- inked to lys on e2 (lipoamide)
- ## accepts hydroxyethyl carbanion from tpp
coenzyme A
stochiometric
- substrate for E2
- accepts aceytl group from lipoamide
FAD flavin
- bound to E3
- reduced by lipoamide
NAD+ catalutic
substrate for E3
reduced by FADH@
Q: What metabolic enzyme does arsenite primarily inhibit?
inhibits pyruvate
what is the first enzyme of tca
citrate synthase
- add acetyl group to oxalocacetate to make citrate
why is succinyl coa synthetase important
- uses SLP
- nucleoside triphosphate is made - atp in most prok
- gtp in euk
- driven by hydrolysis of CoA ester
- inolves phosphohistidine
succinate DH is competitively inhibited why what
malonate making it poison
what is the only enzyme bound of TCA
succinate DH bc its complex 2 of the ETC
what happens during succinate dh
- hydride transfer and oxidation with fad
- fad reduced
what are the characteristics of riboflavin vitamin b12
- coenzyme: FAD, FMN
- oxidation reduction
growth retardation
why is fumarase a bidrecrtional rxn
- lyase reaction
- prochiral differentiation= molecule that is not chiral has the potential to become chiral
what is the product of tca in euk
- 2 co2
- 1 gtp= atp equivalent
- 3 nadh
- 1 fadh2
-(4 reduced coenzues)
how is pyruvate dh regulated
producut inhibition by NADH Nad+ for binding sites e3
-acetyl w/ CoA for binding site e2
what does Pyr. DH do to enzymes E2 and E3
- drive them backwards
- keeps E2 in acetylated form unable to accept hydroxyethyl gp from E1
how to control phosphorylation
- 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
which enzyme is used by reversible phosphorylation of pyruvate DH
enzyme 1
- deacitvated by PDH kinase
what activatdes PDH kinase
- acetyl co a, nadh/Nad+, or ATP
this leads to the deactivation
when does PDH switch off
when the energy is high and biosynthetic intermediates are high
what keeps PDH kinase active
- pyruvate, ADP, Ca+2
- low signal = make atp
enzyme 1 is activated by what in regulation of pDH
-dephosphorylation PDH phophatase
what are some main points of TCA and PDH rxn
- occurs in mito matrix except for succinate DH( membrane bound)
- PDH, citrate synthasae, isocitrate dh, alpha keto dh = irrreversible
- irreversible = regulated
what are the main regulatory enzymes of tca
- isocitrate DH
- PDH
which rxns are inhibited by NADH and ATP
- pdh
-citrate synthase - isocitate
- alpha keto dh
what is the enzyme that makes cycle underectional
alpha keto dh
what does succinal co a synthetase use to generate atp
SLP
what are the anaplerotic reactons and what is anaplerotic
- replenishes intermediates
- Pyruvate carb
-PEP carboxy - malic enzyme
what does pyruvate carb do
- converts pyruvate to oxalocae
found in liver, kidney
what does pep carboxy do
converts PEP –> oxalocaetate
- higher in plants, yeast, bacteria not animals
what does malic enzyme do
pyruv–> malate
widely distributed by prok and euk
what is the role of aspartate transaminase in tca
facilitates the conversion of aspartate ito oxalocaetate , linking nitrogen metabolish with central carbon metabolism
what is the first enzyme of gluconeogenesis
pyruvate carboxylase
what does pyruv carbox do again
- catalyzes the atp and biotin dependent conversionof pyr to oxalocatee in mitochondrial matrix
what happens to carboxyl c of acetate
turns into co2 in the second turn of the cycle
