PPP, Glycogen synthesis, and pyruvate

Question 1

If you want to turn pyruvate into lactate, use what enzyme?

Answer 1

Lactate dehydrogenase

NADH + H+ –> NAD+

Question 2

If pyruvate is turned into ethanol, what enzymes?

Answer 2

Pyruvate decarboxylase (remove CO2) 
Alcohol Dehydrogenase (NADH --> NAD+)

Question 3

Pyruvate –> Oxaloacetate

Answer 3

Pyruvate Carboxylase

Question 4

Pyruvate –> Acetyl-CoA

Answer 4

pyruvate Dehydrogenase

Decarboxylation to make 2C; oxidation of glucose to CO2, which is released.

Question 5

NADH + NDP –> dNP

Answer 5

Ribonucleotide Reductase

Uses NADPH, remember this

Question 6

G6P –> 6-phosphoglucano-delta-lactone

Answer 6

G6P Dehydrogenase
NADP+ –> NADPH + H+

Transfer hydride ion from G6P to NADP+

Question 7

Ribulose-5-phosphate – > Ribose 5 phosphate

Answer 7

Reversible
Ribulose 5 phosphate Isomerase

Isomerization

Question 8

6-phosphoglucano-delta-lactone –> 6-phosphoglyconate

Answer 8

H2O –> H+
RING OPENING

6-phosphoglycano lactonase

Question 9

6-phosphoglyconate –> Ribulose-5-phosphate

Answer 9

6-phosphoglycoante dehydrogenase

NADP+ –> NADPH + CO2
Oxidative decarboxylation
2nd NADPH

Question 10

PhosphoGLYCOmutase

Answer 10

Reversible, G6P –> G1P for degradation

Question 11

What activates G1P with UTP?

Why is the irreversible?

Answer 11

UDP-glucose phosphorylase

Inorganic pyrophosphatase

Coupling with PPi hydrolysis

Question 12

What transfers UDP-glucose to glycogen?

Answer 12

C4 OH- glycogen synthase

C6 OH- transglycosylase

Question 13

Where does glucose-6-phosphatase NOT convert G6P to glucose?

Answer 13

muscle cells

Question 14

Glycogen back to G1P?

Answer 14

Glycogen phosphorylase

Add Pi

Question 15

Why do we use Lactate dehydrogenase

Answer 15

Reoxidize NAD+ during exercise

Question 16

What happens to lactate once we make it?

Answer 16

1) Converted back to pyruvate

2) Exported from cell, liver takes it up, oxidizes back to pyruvate

Question 17

Pyruvate carboxylase mechanism (pyruvate –> oxaloacetate using prosthetic group)

Answer 17

Biotinyl-Lys is group
Biotin carries CO2, covalent to Lys, which swings between active sites.
1. Site 1- Co2 reacts with ATP, ADP release
2. Pi leaves, biotin carboxylated
3. Enzyme abstracts proton, carbanion
4. Site 2- carbanion attacks carboxyl group, generates oxaloacetate from pyruvate.

Question 18

How are the following synthesized?
Lactose-
Starch-
Cellulose-

Answer 18

Lactose: from glucose and UDP-galactose
Starch: ADP-glucose
Cellulose: CDP-glucose

Question 19

Glycogen synthase (UDP-glucose –> C4 OH) subject to

Answer 19

Hormone control

Activation by insulin

Question 20

How do muscle cells conserve 1 ATP?

Answer 20

Start at G6P, does not convert back to glucose

Question 21

what happens to excess carbons of PPP

Answer 21

recycled into intermediates of the glycolytic pathway so that they can be degraded to pyruvate or used in gluconeogenesis, depending on cell type and its metabolic needs.

Question 22

In PPP what enzymes change C5 to C3/C6 carbon units?

Answer 22

Transketolases and tranaldolases

This recycles biproducts