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The enzymatic release of energy from organic compounds (especially carbohydrates and fats) which requires oxygen as the terminal electron acceptor. A pathway leading to the fixation of two molecules of CO2 and the production of one molecule of acetyl-CoA; essentially the oxidative TCA cycle running in reverse. Acetyl-CoA is reductively carboxylated to pyruvate, from which all other central metabolites can be formed. Most of the enzymes of reductive and oxidative TCA cycle are shared, with the exception of three key enzymes that allow the cycle to run in reverse: ATP citrate lyase, 2-oxoglutarate:ferredoxin oxidoreductase, and fumarate reductase. 2-oxoglutarate:ferredoxin oxidoreductase catalyzes the carboxylation of succinyl-CoA to 2-oxoglutarate, ATP citrate lyase the ATP-dependent cleavage of citrate to acetyl-CoA and oxaloacetate, and fumarate reductase the reduction of fumarate forming succinate. The enzymatic release of energy from organic compounds (especially carbohydrates and fats) which either requires oxygen (aerobic respiration) or does not (anaerobic respiration). A nearly universal metabolic pathway in which the acetyl group of acetyl coenzyme A is effectively oxidized to two CO2 and four pairs of electrons are transferred to coenzymes. The acetyl group combines with oxaloacetate to form citrate, which undergoes successive transformations to isocitrate, 2-oxoglutarate, succinyl-CoA, succinate, fumarate, malate, and oxaloacetate again, thus completing the cycle. In eukaryotes the tricarboxylic acid is confined to the mitochondria. See also glyoxylate cycle. The chemical reactions and pathways resulting in the breakdown of coenzymes, any of various nonprotein organic cofactors that are required, in addition to an enzyme and a substrate, for an enzymatic reaction to proceed. The chemical reactions and pathways involving acetyl-CoA, a derivative of coenzyme A in which the sulfhydryl group is acetylated; it is a metabolite derived from several pathways (e.g. glycolysis, fatty acid oxidation, amino-acid catabolism) and is further metabolized by the tricarboxylic acid cycle. It is a key intermediate in lipid and terpenoid biosynthesis. The chemical reactions and pathways resulting in the breakdown of acetyl-CoA, a derivative of coenzyme A in which the sulfhydryl group is acetylated.

View Gene Ontology (GO) Term

GO TERM SUMMARY
Name: tricarboxylic acid cycle
Acc: GO:0006099
Aspect: Biological Process
Desc: A nearly universal metabolic pathway in which the acetyl group of acetyl coenzyme A is effectively oxidized to two CO2 and four pairs of electrons are transferred to coenzymes. The acetyl group combines with oxaloacetate to form citrate, which undergoes successive transformations to isocitrate, 2-oxoglutarate, succinyl-CoA, succinate, fumarate, malate, and oxaloacetate again, thus completing the cycle. In eukaryotes the tricarboxylic acid is confined to the mitochondria. See also glyoxylate cycle.
Synonyms:
  • citric acid cycle
  • TCA cycle
  • Krebs cycle
Proteins in PDR annotated with:
   This term: 402 [Search]
   Term or descendants: 402 [Search]


[geneontology.org]
INTERACTIVE GO GRAPH

GO:0006099 - tricarboxylic acid cycle (interactive image map)
YRC Informatics Platform - Version 3.0
Created and Maintained by: Michael Riffle