Glossary of 3B: CAC

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where does CAC take place
in the mitochondria
how many carboxylic acids are on citrate?
3 - a tricarboxylic acid.
How does pyruvate get from the cytosol to the mito matrix?
by an antiporter, pyruvate carrier.
what happens to pyruvate once it gets into the mito matrix?
it is oxidatively decarboxylated by pyruvate dehydrogenase complex.
what links glycolysis and CAC?
oxidative decarboxylation of pyruvate to give acetyl CoA and CO2
What does CoA do?
carries Acyl groups
What are the components of CoA?

What is the reactive part?
B-mercaptoethylamine unit
Pantothenate Unit

The thiol SH
how does acetate enter the CAC?
thioester bonded to CoA.
what's the diff between ATP and GTP?
adenine and guanine
What is Thiamine Pyrophosphate? (TPP)
The prosthetic group of E1 on pyruvate dehydrogenase complex.
what is the function of TPP?
decarboxylate pyruvate
what is the function of lipoamide?
what is the function of Coenzyme A in PDHC?
Acyl carrier
What is the purpose of FAD in PDHC?
to reoxidize lipoamide
what is the function of NAD+ in PDHC?
to reoxidize FADH2
how come the reactive part of TPP is reactive?
The Carbon atom is between N and S, so very stable anion - acidic; deprotonates because pka is about 10.
Then the anion adds to pyruvate to form tetrahedryl intermediate.
E2 of PDHC
dihydrolipoyl transacetylase
What is E3 of PDHC?
Dihydrolipoyl dehydrogenase

-Oxidizes dihydrolipoamide to regenerate the coenzyme lipoamide.
what is the reactive center of TPP?
a thiazolium ring (acidic carbon between a nitrogen and sulfur)
how many atoms make up the long lipoamide arm of lipoic acid/lysine?
what are the reactions that take place at E1 of PDHC?
1. Decarboxylation - add pyruvate to TPP, give of CO2.

2. Oxidation - oxidize TPP back, transfer Acetyl concomiantly to Lipoamide.
what are the reactions that take place at E2 of PHDC?
only one; transfer of acetyl from acetyllipoamide to CoA to leave dihydrolipoamide (reduced form).
How many enzymes and cofactors are in PDHC
3 enzymes
5 cofactors
What are the 5 cofactors in PDHC
Coenzyme A
What plays a central role in formation of Acetyl CoA from Pyruvate?
What are the steps of PDHC?
1. Thiamine Pyrophosphate decarboxylates
2. Lipoamide Oxidizes the Acetyl group and transfers it to Coenzyme A.
3. FAD reoxidizes Lipoic Acid back to Lipoamide.
4. NAD oxidizes FADH2 back to FAD.
What is lipoamide linked to on WHICH ENZYME?
a Lysine residue on Enzyme 2
What are the cofactors bound to each subunit in TPHC?
E2: Lipoamide, CoA
What is a synthase
an enzyme catalyzing a synthetic reaction in which 2 units are joined w/out participation of ATP or NTP
what are control points for the CAC?
isocitrate dehydrogenase

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