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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Coenzyme A (CoA, CoASH, or HSCoA) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle. All genomes sequenced to date encode enzymes that use coenzyme A as a substrate, and around 4% of cellular enzymes use it (or a thioester, such as acetyl-CoA) as a substrate. It is adapted from cysteamine, pantothenate, and adenosine triphosphate.
Coenzyme A is synthesized in a five-step process from pantothenate and cysteine:
- Pantothenate (vitamin B5) is phosphorylated to 4'-phosphopantothenate by the enzyme pantothenate kinase (PanK; CoaA; CoaX)
- A cysteine is added to 4'-phosphopantothenate by the enzyme phosphopantothenoylcysteine synthetase (PPC-DC; CoaB) to form 4'-phospho-N-pantothenoylcysteine (PPC)
- PPC is decarboxylated to 4'-phosphopantetheine by phosphopantothenoylcysteine decarboxylase (CoaC)
- 4'-phosphopantetheine is adenylylated to form dephospho-CoA by the enzyme phosphopantetheine adenylyl transferase (CoaD)
- Finally, dephospho-CoA is phosphorylated using ATP to coenzyme A by the enzyme dephosphocoenzyme A kinase (CoaE).
Discovery of structure 
Since coenzyme A is, in chemical terms, a thiol, it can react with carboxylic acids to form thioesters, thus functioning as an acyl group carrier. It assists in transferring fatty acids from the cytoplasm to mitochondria. A molecule of coenzyme A carrying an acetyl group is also referred to as acetyl-CoA. When it is not attached to an acyl group, it is usually referred to as 'CoASH' or 'HSCoA'.
List of coenzyme A-activated acyl groups 
- Coumaroyl-CoA (used in flavonoid and stilbenoid biosynthesis)
- Acyl derived from dicarboxylic acids
- Succinyl-CoA (used in heme biosynthesis)
- Hydroxymethylglutaryl-CoA (used in isoprenoid biosynthesis)
- Pimelyl-CoA (used in biotin biosynthesis)
- fatty acyl-CoA (activated form of all fatty acids; only the CoA esters are substrates for important reactions such as mono-, di-, and triacylglycerol synthesis, carnitine palmitoyl transferase, and cholesterol esterification)
- Benzoyl CoA
- Phenylacetyl CoA
- Butyryl CoA
Additional images 
- Matthew Daugherty, Boris Polanuyer, Michael Farrell, Michael Scholle, Athanasios Lykidis, Valérie de Crécy-Lagard and Andrei Osterman (2002). "Complete Reconstitution of the Human Coenzyme A Biosynthetic Pathway via Comparative Genomics". The Journal of Biological Chemistry 277: 21431–21439. doi:10.1074/jbc.M201708200. PMID 11923312.
- Baddiley, J.; Thain, E. M.; Novelli, G. D.; Lipmann, F. (1953). "Structure of Coenzyme A". Nature 171 (4341): 76. doi:10.1038/171076a0.
- Elovson J, Vagelos PR (July 1968). "Acyl carrier protein. X. Acyl carrier protein synthetase". J. Biol. Chem. 243 (13): 3603–11. PMID 4872726.
- Strickland KC, Hoeferlin LA, Oleinik NV, Krupenko NI, Krupenko SA (January 2010). "Acyl carrier protein-specific 4'-phosphopantetheinyl transferase activates 10-formyltetrahydrofolate dehydrogenase". J. Biol. Chem. 285 (3): 1627–33. doi:10.1074/jbc.M109.080556. PMC 2804320. PMID 19933275.
- Karl Miller (1998). Beta Oxidation of Fatty Acids. Retrieved May 18, 2005.
- Charles Ophard (2003). Acetyl-CoA Crossroads. Retrieved May 18, 2005.
- Nelson, David L.; Cox, Michael M. (2005). Lehninger: Principles of Biochemistry (4th ed.). New York: W.H. Freeman. ISBN 0-7167-4339-6.
- Overview of Fatty Acid Oxidation Reactions
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