Pentose Phosphate Pathway Flashcards
What is PPP also known as?
- hexose monophosphate shunt
- phosphogluconate pathway
What is NADPH used in?
anabolism (building of things)
What is NADH used in?
catabolism (breaking down things)
This pathway has two phases: what are they?
oxidative phase - production of energy and pentoses
non-oxidative phase - rearrangement of pentoses (C5) back to hexoses (C6)
Provide a summary of the oxidative phase.
C6 –> C5 + CO2 + 2NADPH + 2H+
Provide a summary of the non-oxidative phase.
C5 –> C6
From 6C6 –> 6C5, how many NADPH are released?
12
How many ATP can be produced from NADPH ?
30 ATP
2.5ATP/NADPH
What are the 2 major reasons for having this pathway?
- produce NADPH - reducing power: needed for reductive biosynthesis or counter damaging effects of oxygen radicals (fat cells or erythrocytes/lenses)
- make pentoses: in bone marrow/skin and intestinal mucosa used for RNA/DNA and coenzymes (ATP, NADH, FADH2, and CoA)
Name the enzyme for:
Glc 6 P –> Gluconolacctone 6-P
Glc 6 P dehydrogenase
Name the enzyme for:
Gluconolactone 6-P –> gluconate 6P
lactonase
Name the enzyme for:
gluconate 6P –> ribulose 5P
gluconate 6P dehydrogenase
Name the enzyme for:
ribulose 5P –> ribose 5P
ribose P isomerase
Name the cofactors for:
Glc 6 P –> Gluconolacctone 6-P
NADP+ –> NADPH + H+
Name the cofactors for:
Gluconolactone 6-P –> gluconate 6P
H2O consumed
Name the cofactors for:
gluconate 6P –> ribulose 5P
NADP+ is converted to NADPH + H+
CO2 released
Name the cofactors for:
ribulose 5P –> ribose 5P
no cofactors
Describe step 1 in the non-oxidative phase of PPP
Ribulose 5P is either converted into:
-xylulose 5P by ribose 5P epimerase
OR
-ribose 5P by ribose P isomerase
Describe step 2 in the non-oxidative phase of PPP
C5 + C5 –> C7 + C3
xylulose 5P + ribose 5P –> glyceraldehyde 3P + sedoheptulose 7P
(uses a transketolase which uses TPP)
Describe step 3 in the non-oxidative phase of PPP
C7 + C3 –> C6 + C4
Ga3P + sedoheptulose 7P –> fructose 6P and erythrose 4P
(uses a transaldolase which uses Schiff-Base linkage)
Describe step 4 in the non-oxidative phase of PPP
C4 + C5 –> C6 + C3
erythrose 4P + xylulose 5P –> fructose 6P + Ga3P
(uses a transketolase TPP)
Describe step 5 in the non-oxidative phase of PPP
C3 + C3 –> C6
Ga3P –> DHAP + Ga3P –> fructose 1,6, bisP —>fructose 6P
Name the enzyme:
Ga3P –> DHAP + Ga3P
triose P isomerase
Name the enzyme:
Ga3P –> fructose 1,6, bisP
aldolase
Name the enzyme:
Fructose 1,6, bisP –> fructose 6 P
Frc 1,6, bisP
