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18 Cards in this Set
- Front
- Back
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What is the citric acid cycle |
oxidation of metabolic fuel, the central pathway for obtaining energy from carbs, fatty acids and amino acids |
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Before entering the citric acid cycle |
fuels are decomposed into two acetyl groups and attach to CoA to form Acetyl-CoA |
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Oxidation of acetyl group forms |
CO2 |
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Overall reaction krebs cycle |
3 NAD + FAD + GDP + Pi + Acetyl CoA-> 3 NADH + FADH2 + GTP + CoA + 2 CO2 acetyl carbons are not the ones in CO2 |
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Citric acid cycle reaction |
has 8 steps, 4 pairs of electrons are released, three consumed in reduction of 3 NAD+ to 3 NADH and FAD to FADH |
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Citrate |
Product of first reaction and has 6 carbons |
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Oxaloacetate |
has 4 carbons , first reactant and final product |
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Other names for citric acid cycle |
Krebs cycle/ tricarboxylic acid cycle |
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Where is free energy of oxidation conserved |
GTP and 4 reduced coenzymes |
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Location |
Mitochondria in eukaryotes and cytoplasm in prokaryotes |
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Synthesis of Acetyl CoA |
formed by multienzyme complex, 3 enzymes: E1:pyruvate dehydrogenase, E2:dihydrolipoyl transacetylase, E3:dihyrolipoyl dehydrogenase, 5 coenzymes: TPP, Lipoic Acid, CoA, NAD+, FAD |
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Role of Pyruvate Dehydrogenase |
Decarboxylates pyruvate, |
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Role of Dihydrolipoyl transacetyase |
transfers acetyl to CoA |
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Role of Dihydrolipoyl dehydrogenase |
Reduces NAD+ to NADH |
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Multienzyme complex |
group of non covalently associated enzymes that catalyze several sequential steps in a pathway, enhances reaction rate by decreasing distance between enzymes, minimizes side reactions, and coordinates control of catalyzed reactions |
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Structure of multienzyme complex |
24 E2 proteins, are trimers at the corner of the complex, 24 E1 forms dimers that associate with E2, 12 E3 forms dimers that associate with faces of the cube |
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Pyr+CoA+NAD+ ->Acetyl CoA + CO2 + NADH |
5 Rxns E1 Decarboxylates pyruvate and forms hydroxyethyl- TPP, Hydroxyethyl transferred to E2 which contains lipoamide group, E2 transfers acetyl to CoA forming Acetyl CoA E3 Oxidizes Acetyl CoA to reform E2 and E3 is now reduced, E3 is reoxidized using FAD which funnels electrons to NAD forming NADH |
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Lipoillysyl Arm in E2 |
14 angstrom long, moves products from one enzyme to another reaction, uses cyclic disulfide group and becomes reduced to bind to acetyl group, |
