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14 Cards in this Set
- Front
- Back
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another name for Pentose Phosphate Pathway
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hexose monophosphate shunt
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2 main function of PPP
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•Provides NADPH for biosynthesis
•Produces ribose-5-P |
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Where does it mostly occur:
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mostly in cytoplasm of liver and adipose cells
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What is NADPH used in?
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cytosol for fatty acid synthesis
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substrate for reaction
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G6P
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What are the three 1st-steps oxidative enzymatic in PPP:
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1. G6P Dehydrogenase
(Irreversible 1st step -highly regulated) 2.Gluconolactonase 3. 6-Phosphogluconate Dehydrogenase (Oxidative decarboxylation) |
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What are the Nonoxidative oxidative enzymatic Steps
in PPP: |
•Phosphopentose isomerase (converts ketoseto aldose)
•Phosphopentose Epimerase (epimerizes at C-3) •Transketolase (TPP-dependent) •Transaldolase (Schiff base mechanism) –transfers a three-carbon unit |
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What are the 4 variations in the PPP?
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1) Both ribose-5-P and NADPH are needed
2) More ribose-5-P than NADPH is needed 3) More NADPH than ribose-5-P is needed 4) NADPH and ATP are needed, but ribose-5-P is not |
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Where do PPP reactions occur?
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only in cytoplasm
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What steps generate the NADPH?
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oxidative steps (1 and 3)
gives net 2 moles per 1 mol of G6P (1 mol per oxidation) |
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What steps generate the ribose-5-phosphate?
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Non-oxidative steps
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What is metabolic difference if more ribose-5-P than NADPH is needed?
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Skips oxidatidive steps, instead G6P -+ATP- F6P continue toward R5P
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What is metabolic difference if More NADPH than ribose-5-P is needed
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In 1st and 2nd steps, 6 NADP+ added each time for oxidation, producing 12 NADPH, end product ribulose-5-P -- 2 R5P
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What is metabolic difference if NADPH and ATP are needed, but ribose-5-P is not
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In 1st and 2nd steps, 3 NADP+ added each time for oxidation, producing 3 NADPH, product ribulose-5-P cont to metob ending with glycolysis = 10 ATP
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