fate of pyruvate & citric acid cycle
DESCRIPTION
Fate of Pyruvate & Citric Acid Cycle. Introduction of Glucose Metabolism Lecture-3. Fate of pyruvate. 1- Lactate (in cytosol ) Enzyme: lactate dehyrogenase (LDH) in anaerobic glycolysis 2- Acetyl CoA in mitochondria Enzyme: pyruvate dehydrogenase - PowerPoint PPT PresentationTRANSCRIPT
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Fate of PyruvateFate of Pyruvate& Citric Acid Cycle& Citric Acid Cycle
Introduction of Glucose Metabolism Introduction of Glucose Metabolism Lecture-3Lecture-3
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Fate of pyruvateFate of pyruvate
1- LactateLactate (in cytosol)(in cytosol) Enzyme: lactate dehyrogenase (LDH)Enzyme: lactate dehyrogenase (LDH) in anaerobic glycolysis
2- Acetyl CoAAcetyl CoA in mitochondriain mitochondria Enzyme: Enzyme: pyruvate dehydrogenasepyruvate dehydrogenase occurs in aerobic glycolysis Acetyl CoA is required for citric acid cycle (CAC)
3- OxalacetateOxalacetate in mitochondriain mitochondria EnzymeEnzyme: : pyruvate carboxylase pyruvate carboxylase Oxalacetate is required for: 1- Citric acid cycle (condenses with acetyl CoA): to yield energy ATP OR 2-Gluconeogenesis (to synthesize glucose)
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LACTATELACTATE
Oxygen&
Mitochondria
No OxygenNo Mitochondria
OR BOTH
GlucoseGlucose
PYRUVATEPYRUVATE
ACETYL CoAACETYL CoA
CITRIC ACID CYCLECITRIC ACID CYCLE
OXALACETATEOXALACETATE
Fate ofFate of PyruvatePyruvate
glycolysisGluconeogenesis
mitochondria
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LACTATE DEHYDROGENASELACTATE DEHYDROGENASE
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FATES OF PYRUVATEFATES OF PYRUVATE
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OXIDATIVE DECARBOXYLATION OF PYRUVATEOXIDATIVE DECARBOXYLATION OF PYRUVATE
Allosteric Regulation
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Formation of acetyl CoA from pyruvateFormation of acetyl CoA from pyruvate
• Pyruvate (end product of aerobic glycolysis) is transported into the mitochondria.
• In the mitochondrial matrixmitochondrial matrix, pyruvate is converted to acetyl CoA acetyl CoA by pyruvate dehydrogenase complex pyruvate dehydrogenase complex (multienzyme complex) This reaction is irreversible
• Pyruvate dehydrogenase complex Pyruvate dehydrogenase complex is composed of three enzymes & five coenzymes
• Coenzymes of the complex Coenzymes of the complex are derived from water soluble vitamins:
1- Thiamine pyruphosphate, TPP Thiamine pyruphosphate, TPP (derived from thiamine, vitamin B1) 2- NAD+NAD+ (derived from niacin) 3- FAD FAD (derived from riboflavin) 4- Lipoic acidLipoic acid 5- Coenzyme ACoenzyme A (derived from pantothenic acid)
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Pyruvate dehydrogenase Pyruvate dehydrogenase complexcomplex
PYRUVATEPYRUVATEACETYL CoAACETYL CoA
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Citric acid cycle Citric acid cycle or,(Krebs cycle)(Krebs cycle)
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Citric Acid CycleCitric Acid Cycle
Citric acid cycleCitric acid cycle is the final pathway where the oxidative metabolism of
CarbohydratesCarbohydrates (as glucose), proteinsproteins (amino acids) & lipidslipids (fatty acids) to yield energy (ATPATP)
Acetyl CoA Acetyl CoA is the end product for oxidation of carbohydrates, lipids & proteinsAcetyl CoA Acetyl CoA condenses with oxalacetate oxalacetate to form citrate (first reaction of the cycle)
3 NADH are produced = 3 X 3 = 9 ATP (by oxidative phosphorylation)9 ATP (by oxidative phosphorylation)One FADH2 is produced = 1 X 2 = 2 ATP (by oxidative phosphorylation)2 ATP (by oxidative phosphorylation)
One ATP One ATP is produced (by substrate level phosphorylationby substrate level phosphorylation)Net = 12 ATP / one acetyl CoANet = 12 ATP / one acetyl CoA
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Citric Acid Cycle CYCLE - SUMMARYCitric Acid Cycle CYCLE - SUMMARY
Acetyl CoA3 NAD
3 NADH + H
1 FAD
1 FADH2
1 ADP1 ATP
2 CO2
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KREBS CYCLE REACTIONS (1)KREBS CYCLE REACTIONS (1)
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KREBS CYCLE REACTIONS (2)KREBS CYCLE REACTIONS (2)
Succinate Succinate ThiokinaseThiokinase
Substrate-LevelPhosphorylation
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KREBS CYCLE REACTIONS (3)KREBS CYCLE REACTIONS (3)
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KREBS CYCLE: ENERGY YIELDKREBS CYCLE: ENERGY YIELD
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Citric acid cycle Citric acid cycle or,(Krebs cycle)(Krebs cycle)