Pyruvic acid (top), acetoacetic acid and levulinic acid (bottom)<unk> s or<unk> s (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group and a<unk> ne group. In several cases, the<unk>  group is hydrated. The alpha-keto acids are especially important in biology as they are involved in the Krebs citric acid cycle and in glycolysis. Common types of<unk> s include: *Alpha-keto acids, Alpha-ketoacids, or 2-oxoacids have the<unk>  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. Furthermore, alpha-keto acids such as phenylpyruvic acid are endogenous sources for carbon monoxide (as a gasotransmitter) and pharmaceutical prodrug scaffold.Important representatives: *pyruvic acid, pervasive intermediate in metabolism. *oxaloacetic acid, a component of the Krebs cycle. *alpha-ketoglutarate, a 5-carbon<unk>  derived from glutamic acid. Alpha-ketoglutarate participates in cell signaling by functioning as a coenzyme. It is commonly used in transamination reactions. *Beta-keto acids, Beta-ketoacids, or 3-oxoacids, such as acetoacetic acid, have the<unk> ne group at the second carbon from the carboxylic acid. They generally form by the Claisen condensation. *Gamma-keto acids, Gamma-ketoacids, or 4-oxoacids have the<unk> ne group at the third carbon from the carboxylic acid. Levulinic acid is an example.<unk> s 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 coniine alkaloids. When ingested sugars and carbohydrate levels are low, stored fats and proteins are the primary source of energy production. Glucogenic amino acids from proteins are converted to glucose.<unk> genic amino acids can be deaminated to produce alpha<unk> s and<unk> ne bodies. Alpha<unk> s are used primarily as energy for liver cells and in fatty acid synthesis, also in the liver.
Keto acid
Beta-Hydroxy beta-methylbutyric acid
Phenylacetic acid
Choline
Cholesterol
Trace amine
Gamma-Amino-beta-hydroxybutyric acid
3-Indolepropionic acid