Biochemistry 514 Exam Ii: Pyruvate Metabolism

Front 1

Aspartate-glutamate transporter & Malate-alpha-ketoglutarate transporter found?

Back 1

Inner mitochondrial matrix because it is impermeable to small molecules and maintains membrane potential.

Front 2

In what conditions
(anerobic/aerobic) facilitates the conversion of pyruvate to acetyl-coA?

Back 2

In aerobic, bc if in anerobic, need some pyruvate in the cytosol to be converted to lactate. Need to maintain NAD/NADH for glycolysis.

Front 3

Pyruvate + NAD+ + CoA--->Acetyl-CoA + NADH+ CO2

Back 3

This step is irreversible
Pyruvate Dehydrogenase (PDH)

Front 4

ADP, Insulin turn pyruvate metabolism on/off?

Back 4

On

Front 5

Glucagon turns pyruvate metabolism on/off?

Back 5

Off

Front 6

The fates of pyruvate

Back 6

1. Lactate
2. Alanine for protein synthesis
3. OAA
4. Acetyl CoA
a. TCA cycle for ATP
b. Steroids
c. fat

Front 7

Pyruvate Dehydrogenase (PDH) complex large because?

Back 7

1. enhance rate of sequential reactions
2. minimize side reactions
3. stabilize against proteolysis (strengh in numbers)
4. permit coordinated regulation

Contains E1, E2 & E3, 5 cofactors

Front 8

Cofactors of PDH

Back 8

1. Coenzyme A
2. Thiamine Pyrophosphate (TPP)
3. NAD
4. FAD
5. Lipolic acid

Front 9

Thiamine Pyrophosphate

Back 9

Tightly bound to E1
Accepts 2 carbons from pyruvate and transfers them to make Acetyl CoA

Front 10

Lipoic acid/lipoamide

Back 10

-Covalently bound to E2
-Hook up with Lysine to get long arm, which reaches from E1, E2, and E3 to accommplish transfer.
-Inhibition by arsenic

Front 11

Pyruvate + NAD+ HSCoA -->AcCoA + NADH +CO2 How?

Back 11

1. PDH w/ 3 E + Cofactors bound
2. Decarboxylate pyruvate & transfer to TPP (E1)
3. Oxidation of alcohol and transfer to Lipolic acid on E2
4. Lipolic acid transfers 2 Carbons to Acetyl-CoA
5. Now have reduced S groups-must be oxidized on Lipolic acid
6. Transfer H to FAD-->FADH2 on E3
7. Don't want FADH2, but FAD and so therefore transfer H's to NAD--> NADH

Front 12

Negative regulators of PDH

Back 12

Direct: Inhibited by pds (Ac.CoA & NADH)
Indirect: Pds (Ac.CoA & NADH) active kinase which phosphorylates PDH--> inactive

Front 13

Positive regulators of PDH

Back 13

Direct: Signals of low energy (AMP, GDP)
Indirect: Pyruvate, CoASH, NAD which inhibit kinase-->PDH unphoshorylated-->active

Front 14

Hormonal regulation

Back 14

Insulin-high blood sugar activates PDH through phosphatase (unphosphorylate it)