PPP, Glycogen synthesis, and pyruvate Flashcards
If you want to turn pyruvate into lactate, use what enzyme?
Lactate dehydrogenase
NADH + H+ –> NAD+
If pyruvate is turned into ethanol, what enzymes?
Pyruvate decarboxylase (remove CO2) Alcohol Dehydrogenase (NADH --> NAD+)
Pyruvate –> Oxaloacetate
Pyruvate Carboxylase
Pyruvate –> Acetyl-CoA
pyruvate Dehydrogenase
Decarboxylation to make 2C; oxidation of glucose to CO2, which is released.
NADH + NDP –> dNP
Ribonucleotide Reductase
Uses NADPH, remember this
G6P –> 6-phosphoglucano-delta-lactone
G6P Dehydrogenase
NADP+ –> NADPH + H+
Transfer hydride ion from G6P to NADP+
Ribulose-5-phosphate – > Ribose 5 phosphate
Reversible
Ribulose 5 phosphate Isomerase
Isomerization
6-phosphoglucano-delta-lactone –> 6-phosphoglyconate
H2O –> H+
RING OPENING
6-phosphoglycano lactonase
6-phosphoglyconate –> Ribulose-5-phosphate
6-phosphoglycoante dehydrogenase
NADP+ –> NADPH + CO2
Oxidative decarboxylation
2nd NADPH
PhosphoGLYCOmutase
Reversible, G6P –> G1P for degradation
What activates G1P with UTP?
Why is the irreversible?
UDP-glucose phosphorylase
Inorganic pyrophosphatase
Coupling with PPi hydrolysis
What transfers UDP-glucose to glycogen?
C4 OH- glycogen synthase
C6 OH- transglycosylase
Where does glucose-6-phosphatase NOT convert G6P to glucose?
muscle cells
Glycogen back to G1P?
Glycogen phosphorylase
Add Pi
Why do we use Lactate dehydrogenase
Reoxidize NAD+ during exercise
What happens to lactate once we make it?
1) Converted back to pyruvate
2) Exported from cell, liver takes it up, oxidizes back to pyruvate
Pyruvate carboxylase mechanism (pyruvate –> oxaloacetate using prosthetic group)
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.
How are the following synthesized?
Lactose-
Starch-
Cellulose-
Lactose: from glucose and UDP-galactose
Starch: ADP-glucose
Cellulose: CDP-glucose
Glycogen synthase (UDP-glucose –> C4 OH) subject to
Hormone control
Activation by insulin
How do muscle cells conserve 1 ATP?
Start at G6P, does not convert back to glucose
what happens to excess carbons of PPP
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.
In PPP what enzymes change C5 to C3/C6 carbon units?
Transketolases and tranaldolases
This recycles biproducts
