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The pyruvate produced by glycolysis is an important intermediary in the conversion of carbohydrates into fatty acids and cholesterol. [46] This occurs via the conversion of pyruvate into acetyl-CoA in the mitochondrion .
Pyruvate, the conjugate base, CH 3 COCOO −, is an intermediate in several metabolic pathways throughout the cell. Pyruvic acid can be made from glucose through glycolysis , converted back to carbohydrates (such as glucose) via gluconeogenesis , or converted to fatty acids through a reaction with acetyl-CoA . [ 3 ]
Pyruvate kinase is the enzyme involved in the last step of glycolysis. It catalyzes the transfer of a phosphate group from phosphoenolpyruvate (PEP) to adenosine diphosphate (ADP), yielding one molecule of pyruvate and one molecule of ATP . [ 1 ]
Pyruvate is the terminal electron acceptor in lactic acid fermentation. When sufficient oxygen is not present in the muscle cells for further oxidation of pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by reduction of pyruvate to lactate. [4] Lactate is converted to pyruvate by the enzyme lactate dehydrogenase. [3]
Pyruvate dehydrogenase catalyses the rate-limiting step in the aerobic oxidation of glucose and pyruvate and links glycolysis to the tricarboxylic acid cycle (TCA). DCA acts a structural analog of pyruvate and activates the pyruvate dehydrogenase complex (PDC) to inhibit pyruvate dehydrogenase kinases, to keep the complex in its un ...
The second substrate-level phosphorylation occurs by dephosphorylating phosphoenolpyruvate, catalyzed by pyruvate kinase, producing pyruvate and ATP. During the preparatory phase, each 6-carbon glucose molecule is broken into two 3-carbon molecules. Thus, in glycolysis dephosphorylation results in the production of 4 ATP.
Pyruvate oxidation is the step that connects glycolysis and the Krebs cycle. [4] In glycolysis, a single glucose molecule (6 carbons) is split into 2 pyruvates (3 carbons each). Because of this, the link reaction occurs twice for each glucose molecule to produce a total of 2 acetyl-CoA molecules, which can then enter the Krebs cycle.
In eukaryotes, glycolysis occurs in the cytoplasm, pyruvate decarboxylation in the mitochondria, the citric acid cycle within the mitochondrial matrix, and oxidative phosphorylation via the electron transport chain on the mitochondrial cristae. Thus pyruvate dehydrogenase complexes (containing the dihydrolipoyl transacetylase enzymes) are found ...