Citric Acid Cycle

spinqualitylabelsall models Open conformation of citrate synthase dimer complex with citrate (PDB code 1cts) and closed conformation of citrate synthase dimer complex with citrate and CoA (PDB code 2cts) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D A Citric Acid Cycle Schematic The Citric Acid Cycle is a key metabolic pathway that connects carbohydrate, fat, and protein metabolism!!! See also [1]. Krebs cycle importance Krebs cycle overview Krebs cycle reactions The Citric Acid Cycle (tricarboxylic acid cycle) is a series of enzyme catalyzed reactions which are critical in cellular respiration. Under oxidative conditions, pyruvate continues to be metabolized through the tricarboxylic acid cycle. In this cycle, Acetyl-CoA, a byproduct of glycolysis, along with various cofactors, are broken down into carbon dioxide, water, and energy in the form of GTP and NADH. Pyruvate dehydrogenase The multienzyme complex together catalyzes five distinct reactions in the conversion of pyruvate to acetyl-CoA. The overall result is described by the following reaction: Pyruvate + CoA + NAD+ ==> Acetyl-CoA + CO2 + NADH However, pyruvate dehydrogenase (E1) is responsible for only the first two of the five reactions. The first of these is the decarboxylation of pyruvate and coupling of thiamine pyrophosphate (TPP) to form hydroxyethyl-TPP. Pyruvate + TPP ==> Hydroxyethyl-TPP + CO2 Step 0 / 10 - Aldol condensation - Citrate synthase Citrate Synthase Step 0 / 10 = Krebs cycle step 1 ATP-citrate synthase Step 1 - Dehydration - Aconitase Aconitase 1st step of Krebs cycle step 2 Step 2 - Hydration - Aconitase Aconitase 2nd step of Krebs cycle step 2 Step 3 - Oxidation - Isocitrate dehydrogenase Isocitrate dehydrogenase 1st step of Krebs cycle step 3 Step 4 - Decarboxylation - Isocitrate dehydrogenase Isocitrate dehydrogenase 2nd step of Krebs cycle step 3 Step 5 - Oxidative decarboxylation - α-Ketoglutarate dehydrogenase (2-Oxoglutarate Dehydrogenase) 2-Oxoglutarate Dehydrogenase Step 5 = Krebs cycle step 4 Articles in Proteopedia concerning Citric Acid Cycle include: Citrate Synthase Structure & Mechanism Aconitase Isocitrate Dehydrogenase 2-Oxoglutarate Dehydrogenase (also known as alpha-ketoglutarate dehydrogenase) Succinyl-CoA Synthetase Succinate Dehydrogenase Fumarase Malate Dehydrogenase Glutamate Dehydrogenase To view Citric Acid Cycle related proteins which are Structure Index entries see: Aconitase To view automatically seeded indices concerning Citric Acid Cycle See: Citric Acid Cycle

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Alexander Berchansky, David Canner, Ann Taylor, Wayne Decatur, Jaime Prilusky