Pentose Phosphate Pathway Flashcards
What is the pentose phosphate pathway?
it is an oxidative pathway that is alternative to glycolysis. It is most prominent in highly metabolically active tissues.
What are the 2 functions of the pathway?
-reduces NADP+ to NADPH
-produces ribose-5-phosphate
Why does NADP+ need to be reduced to NADPH?
lipid synthesis and it is an important antioxidant
Why do we need to produce ribose-5-phosphate?
-dna and rna synthesis
-ATP
-NAD, FAD, coenzyme A, etc.
What does the oxidative phase do?
-produces ribose-5-phosphate
-reduces NADP+ to NADPH
-involves 4 steps
What are important points of the oxidative phase?
-first and rate limiting reaction is catalyze by G6PD
-reduces 2 mol of NADP+ to NADPH
-results in formation of on mol of ribose-5-phosphate
-one CO2 released by oxidative decarboxylation
-sometimes, pathway can end here
What does the non oxidative phase do?
-active when requirement for NADPH exceeds requirement for ribose-5-phosphate
-this occurs when los of lipid synthesis is happening, need for antioxidant NADPH, and there is little to no need for ribose-5-phosphate
-serves to recycle ribose-5-phosphate back to glucose-6-phosphate
What forms during the non oxidative phase?
six pentoses form five hexoses
What forms during the non oxidative phase?
six pentoses form five hexoses
What are important points of the non oxidative phase?
-serves to recycle ribose-5-phosphate
-series of rearrangements converts 6 five-carbon sugar phosphates to 5 sic-carbon sugar phosphates
-continued cycling converts glucose-6-phosphate to CO2
What is nucleotide synthesis?
when need for nucleotides is high (rapidly dividing cells), the main product is ribose-5-phosphate
What is NADPH synthesis?
When need for NADPH is greatest (for fat synthesis or in red blood cells), fructose-6-phosphate is recycled to glucose-6-phosphate
What is ATP generation?
If needs for NADPH and ribose-5-phosphate are low, the pathway can contribute to ATP generation
G6PD deficiency:
-most common genetic abnormality in the world, usually asymptomatic
What is Favism?
-caused by consumption of fava beans
-contain compounds that inhibit G6PD
-people with G6PD deficiency often get severe hemolytic anemia in response to fava beans
