Alpha-keto acids, alpha-ketoacids, or 2-oxoacids have the keto group adjacent to the carboxylic acid. They often arise by
oxidative deamination of
amino acids, and reciprocally, they are
precursors to the same. Alpha-keto acids possesses extensive chemistry as
acylation agents.[3] Furthermore, alpha-keto acids such as
phenylpyruvic acid are endogenous sources for
carbon monoxide (as a
gasotransmitter) and pharmaceutical
prodrug scaffold.[4] Important representatives:
pyruvic acid, pervasive intermediate in metabolism.
Beta-keto acids, beta-ketoacids, or 3-oxoacids, such as
acetoacetic acid, have the ketone group at the second carbon from the carboxylic acid. They generally form by the
Claisen condensation. The presence of the keto group at the beta position allows them to easily undergo thermal
decarboxylation.[7]
Gamma-keto acids, Gamma-ketoacids, or 4-oxoacids have the ketone group at the third carbon from the carboxylic acid.
Levulinic acid is an example.
Keto acids appear in a wide variety of anabolic pathways in metabolism. For instance, in plants (specifically, in
hemlock,
pitcher plants, and
fool's parsley), 5-oxo-octanoic acid is converted in enzymatic and non-enzymatic steps into the
cyclic class of
coniinealkaloids.[8]
^Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim.
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10.1002/14356007.a18_313
^Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000.
ISBN1-57259-153-6.
^Penteado, Filipe; Lopes, Eric F.; Alves, Diego; Perin, Gelson; Jacob, Raquel G.; Lenardão, Eder J. (16 April 2019). "α-Keto Acids: Acylating Agents in Organic Synthesis". Chemical Reviews. 119 (12): 7113–7278.
doi:
10.1021/acs.chemrev.8b00782.
PMID30990680.
S2CID119535331.
^Kerber, Robert C.; Fernando, Marian S. (October 2010). "α-Oxocarboxylic Acids". Journal of Chemical Education. 87 (10): 1079–1084.
doi:
10.1021/ed1003096.
^Hewitson, K.S.; McNeill, L.A.; Elkins, J.M.; Schofield, C.J. (1 June 2003). "The role of iron and 2-oxoglutarate oxygenases in signalling". Biochemical Society Transactions. 31 (3): 510–515.
doi:
10.1042/bst0310510.
PMID12773146.