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Acetyl-CoA
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<p>Acetyl-CoA (acetyl coenzyme A) is a <a href="/facts/Molecule/N9ljSfFq">molecule</a> that participates in many <a href="/facts/Biochemical_reaction/fa2pWEBp">biochemical reactions</a> in protein, carbohydrate and lipid <a href="/facts/Metabolism/WxDrm8k5">metabolism</a>. Its main function is to deliver the <a href="/facts/Acetyl/rRmtXdn3">acetyl</a> group to the <a href="/facts/Citric_acid_cycle/EGJL9NXP">citric acid cycle</a> (Krebs cycle) to be <a href="/facts/Oxidation/Pyd5RVcj">oxidized</a> for energy production. </p><p><a href="/facts/Coenzyme_A/loAfeGpx">Coenzyme A</a> (CoASH or CoA) consists of a <a href="/facts/Cysteamine/sRnV862R">β-mercaptoethylamine group</a> linked to <a href="/facts/Pantothenic_acid/18EWLroq">pantothenic acid</a> (vitamin B5) through an <a href="/facts/Amide_linkage/3FeX8M6q">amide linkage</a> and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the <a href="/facts/Sulfhydryl/VemKEDP9">sulfhydryl</a> substituent of the β-mercaptoethylamine group. This <a href="/facts/Thioester/UwfKqs1F">thioester</a> linkage is a "high energy" bond, which is particularly reactive. <a href="/facts/Hydrolysis/JTvwIHPs">Hydrolysis</a> of the thioester bond is <a href="/facts/Exergonic/2kPJobE7">exergonic</a> (−31.5 kJ/mol). </p><p>CoA is acetylated to acetyl-CoA by the breakdown of <a href="/facts/Carbohydrates/Geuuzxsf">carbohydrates</a> through <a href="/facts/Glycolysis/a5ApxLoG">glycolysis</a> and by the breakdown of <a href="/facts/Fatty_acids/JGg3erIu">fatty acids</a> through <a href="/facts/Beta_oxidation/mbwIMN7D">β-oxidation</a>. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and water, and the energy released is captured in the form of 11 <a href="/facts/Adenosine_triphosphate/nB9bwgcU">ATP</a> and one <a href="/facts/Guanosine_triphosphate/NAwoHjTW">GTP</a> per acetyl group. </p><p><a href="/facts/Konrad_Bloch/cvYYIfoH">Konrad Bloch</a> and <a href="/facts/Feodor_Lynen/ooLr9Rzu">Feodor Lynen</a> were awarded the 1964 <a href="/facts/Nobel_Prize_in_Physiology_or_Medicine/rlnpJX84">Nobel Prize in Physiology or Medicine</a> for their discoveries linking acetyl-CoA and fatty acid metabolism. <a href="/facts/Fritz_Lipmann/JU0PXDPd">Fritz Lipmann</a> won the Nobel Prize in 1953 for his discovery of the cofactor <a href="/facts/Coenzyme_A/loAfeGpx">coenzyme A</a>. </p>