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Fates of pyruvate under anaerobic conditions: 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 ...
Under these conditions, acetyl-CoA is diverted to the formation of acetoacetate and beta-hydroxybutyrate. [10] Acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone , are frequently, but confusingly, known as ketone bodies (as they are not "bodies" at all, but water-soluble chemical substances).
The pyruvate produced by glycolysis is an important intermediary in the conversion of carbohydrates into fatty acids and cholesterol. [7] This occurs via the conversion of pyruvate into acetyl-CoA in the mitochondrion. However, this acetyl-CoA needs to be transported into cytosol where the synthesis of fatty acids and cholesterol occurs.
The liver in mammals gets rid of this excess lactate by transforming it back into pyruvate under aerobic conditions; see Cori cycle. Fermentation of pyruvate to lactate is sometimes also called "anaerobic glycolysis", however, glycolysis ends with the production of pyruvate regardless of the presence or absence of oxygen.
By using one ATP and bicarbonate, pyruvate will be converted to oxaloacetate, catalysed by pyruvate carboxylase. The PEPC-K enzyme will catalyze oxaloacetate to generate phosphoenolpyruvate . This phosphorylation and decarboxylation of oxaloacetate is a significant step in glyceroneogenesis, since it regulates the entire pathway.
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 ]
Insulin stimulates the activity of pyruvate dehydrogenase phosphatase. The phosphatase removes the phosphate from pyruvate dehydrogenase activating it and allowing for conversion of pyruvate to acetyl-CoA. This mechanism leads to the increased rate of catalysis of this enzyme, so increases the levels of acetyl-CoA.
This reaction is essential for the subsequent steps in beta oxidation that lead to the production of acetyl-CoA, NADH, and FADH2, which are important for generating ATP, the energy currency of the cell. Long-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency is a condition that affects mitochondrial function due to enzyme impairments.