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Gluconeogenesis
- -Synthesis of Glucose from non-hexose precursors
- -Occurs in all animals plants fungi and micro-organisms
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Where does gluconeogenesis occur
- 95% in liver
- some in kidney
- (Glucose-6-phosphatase only exists in liver and kidney)
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What precursors do animals use for gluconeogenesis?
Lactate, pyruvate, glycerol, and amino acids
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What precursors do plants use for glyconeogenesis?
stored fats, proteins sucrose
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What precursors do micro-organisms use for glyconeogenesis?
simple organic compounds: acetate, lactate, propionate Glucose
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What are the 3 bypass reactions in gluconeogenesis that differ from glycolosis?
- 1) Pyruvate oxaloacetate
- oxaloacetate phosphoenolpyruvate
2) fructose 1,6-phosphate fructose 6-phosphate
3) Glucose 6-Phosphate Glucose
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Pyruvate to oxaloacetate
- Pyruvate+CO2+ATPADP+Pi+Oxaloacetate
- Enz: Pyruvate Carboxylase with Bioitin Prosthesis
- Irreversable
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Biotin (B7)
a coenzyme for carboxylase enzymes, involved in the synthesis of fatty acids, isoleucine, and valine, and in gluconeogenesis.
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Oxaloacetate to phosphoenolpyruvate
- Oxaloaceetate+GTPCO2+GDP+phosphoenolpyruvate
- Enz: PEP carboxykinase
- **Oxaloacetate is essentially just phosphoralized
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If Oxaloaceetate phosphoenolpyruvate reaction occurs outside of mitochondria what what must occur?
- Oxaloacetate+NADHNAD++Malate
- (to transport out of mitochondria)
- Enz: Mitochondrial Malate Dehydrogenase
- Malate+NAD+NADH+Oxaloacetate
- (to proceed with reaction)
- Enz: cytosolic Malate Dehydrogenase
**Oxaloacetate can not be transported out of mitochondria
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Fructose 1,6-phosphate Fructose 6-phosphate
- Fructose 1,6-phosphate+H2O
- Pi+Fructose 6-phosphate
- Enz: Fructose 1,6-biphosphatase(FBPase-1)
- irreversable
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Glucose-6-phosphate Glucose
- Glucose-6-phosphate+H2O Glucose+Pi
- irreversable
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At what reactions are the 11 ATP equivalences required?
- 1)2 ATP Pyruvate-oxaloacetate
- 2)2 GTP Oxaloacetate-PEP
- 3)2 ATP 3-phosphoglycerate-1,3bisphosphoglycerate
- 4) 2 NADH 1,3phosphoglycerate-Glyceraldehyde 3-P
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