Pentose Phosphate Pathway (Shunt) Flashcards
When the irreversible (redox) pathway occurs in the liver and RBC, what is the purpose?
To generate NADPH for antioxidant protection for function of the enzyme glutathione reductase
When the irreversible (redox) pathway occurs in the liver only, what is the purpose?
To generate NADPH for fatty acid synthesis and cholesterol synthesis
After the liver has synthesized cholesterol through the irreversible (redox) pathway, what can be done with the cholesterol?
Cholesterol can be converted to steroid hormones, Vitamin D, and bile acids/salts
What is the first step of the irreversible (redox) pathway?
What enzyme is involved?
Glucose 6P + NADP+ -> 6P gluconate + NADPH
Enzyme: glucose 6P dehydrogenase
What is the second step of the irreversible (redox) pathway?
What enzyme is involved?
6P gluconate + NADP+ -> ribulose 5P + CO2 + NADPH
Enzyme: 6P gluconate dehydrogenase
When the reversible portion of the pathway occurs in the liver only, what is the purpose?
Use ribose 5P for nucleotide synthesis
What are the following examples of: ATP, GTP, CTP, UTP, NAD+, FAD, NADP+
Nucleotides
What reaction occurs in the liver in the reversible portion of the pathway?
Ribulose 5P + ribulose 5P -> Xylulose 5P + ribose 5P (epimerase and isomerase)
What is the purpose of the reversible portion of the pathway in RBC?
For fructose 6P and glyceraldehyde 3P to reenter glycolysis
reversible portion (liver & RBC)
Ribulose 5P + Ribulose 5P ->
Xylulose 5P + ribose 5P (epimerase and isomerase)
reversible portion in RBC
Xylulose 5P + ribose 5P ->
Glyceraldehyde 3P + Sedoheptulose 7P (transketolase)
reversible portion in RBC
Glyceraldehyde 3P + sedoheptulose 7P ->
Fructose 6P + erythrose 4P (transaldolase)
reversible portion in RBC
Once glyceraldehyde 3P + sedoheptulose 7P -> fructose 6P + erythrose 4P, what happens to fructose 6P?
Fructose 6P reenters glycolysis
Erythrose 4P + Ribulose 5P ->
Glyceraldehyde 3P + fructose 6P
Once eythrose 4P + ribulose 5P -> glyceraldehyde 3P + fructose 6P, what happens?
Both glyceraldehyde 3P and fructose 6P reenter glycolysis