BCH4024 - Allen Lecture 22 - 23

BCH4024 - Allen Lecture 22 - 23 - Gluconeogenesis Synthesis...

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Unformatted text preview: Gluconeogenesis Synthesis of glucose from small molecular precursors Pyruvate Lactate TCA cycle intermediates Some amino acid skeletons 2 Pyruvate + 4 ATP + 2 GTP + 2 NADH Glucose + 4 ADP + 2 GDP + 2 NAD + + 6 P i glucose Hexokinase glucose -6- phosphate Phosphoglucose Isomerase fructose -6- phosphate Phosphofructokinase - I fructose 1,6- bisphosphate Aldolase Triose phosphate isomerase dihydroxyacetone phosphate glyceraldehyde -3-phosphate Glyceraldehyde -3- phosphate Dehydrogenase 1,3- bisphosphoglycerate Phosphoglycerate Kinase 3 -phosphoglycerate Phosphoglyceromutase 2- phosphoglycerate Enolase phosphoenolpyruvate Pyruvate kinase pyruvate ATP ADP ATP ADP ADP ATP NAD + + P i NADH H 2 O ADP ATP malate oxaloacetate malate oxaloacetate mitochondrion NAD + NADH NAD + NADH GTP GDP + CO 2 ADP ATP + CO 2 Pyruvate carboxylase PEP carboxy kinase Fructose-1,6- bisphosphatase Glucose 6- phosphatase luconeogenesis + P I lactate see also p 544 Lehn p 544 Lehn Synthesis of PEP from Pyruvate (By-Pass Pyruvate Kinase) 1. Pyruvate Carboxylase- mitochondrial enzyme- requires biotin as cofactor- acetyl CoA is required activator- product is reduced to malate in mitochondrion 2. Phosphoenolpyruvate Carboxy Kinase- cytosolic enzyme which requires GTP as energy source- substrate oxaloacetate is derived from oxidation of malate in cytosol Overall Pyruvate + ATP + GTP PEP + ADP + GDP +P i Reaction O OH O OH O O Pyruvate Oxaloacetate + ADP + P i + CO 2 + ATP HO O OH O O Phosphoenolpyruvate Oxaloacetate + GDP + CO 2 + GTP HO O OH O PO 4 2- see also p 545 Lehn ( PEP ) 3. Fructose - 1, 6 bisphosphatase (FBPase 1) fructose 1,6 bisphosphate + H 2 O Fructose -6- P + P i- highly exergonic, irreversible- by-passes phosphofructokinase reaction- highly regulated 4. Glucose - 6 - phosphatase glucose - 6 - phosphate + H 2 O glucose + Pi- highly exergonic, irreversible- by-passes hexokinase reaction- not present in muscle p 547 Lehn 5. 5....
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This note was uploaded on 03/15/2010 for the course BCH 4024 taught by Professor Allison during the Spring '08 term at University of Florida.

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BCH4024 - Allen Lecture 22 - 23 - Gluconeogenesis Synthesis...

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