Keto acid
Encyclopedia
Keto acids are organic compound
s that contain a carboxylic acid
group and a ketone
group. The alpha-keto acids are especially important in biology as they are involved in the Krebs citric acid cycle and in glycolysis
. In several cases, the keto group is hydrated.
Common types of keto acids include:
Amino acids can be deaminated to produce alpha keto acids. Alpha keto acids are used primarily as energy for liver cells and in fatty acid synthesis
, also in the liver.
Under starvation
conditions, stored fats and proteins are the primary means of energy production. Proteins are converted to glucose
and Fats can be used to form Ketone bodies
. In this situation, proteins are converted to amino acids, which are then converted in the liver to alpha keto acids. The alpha keto acids are then converted by the liver to glucose in a process called gluconeogenesis
.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
s that contain a carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
group and a ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
group. The alpha-keto acids are especially important in biology as they are involved in the Krebs citric acid cycle and in glycolysis
Glycolysis
Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+...
. In several cases, the keto group is hydrated.
Common types of keto acids include:
- Alpha-keto acids, or 2-oxoacids, such as pyruvic acidPyruvic acidPyruvic acid is an organic acid, a ketone, as well as the simplest of the alpha-keto acids. The carboxylate ion of pyruvic acid, CH3COCOO−, is known as pyruvate, and is a key intersection in several metabolic pathways....
, have the keto group adjacent to the carboxylic acid. Other important members are oxaloacetic acidOxaloacetic acidOxaloacetic acid is an organic compound with the chemical formula C4H4O5 or HOOC---COOH. It also has other names ....
and glycolic acidGlycolic acidGlycolic acid is the smallest α-hydroxy acid . This colorless, odorless, and hygroscopic crystalline solid is highly soluble in water. It is used in various skin-care products. Glycolic acid is found in some sugar-crops...
. - Beta-keto acids, or 3-oxoacids, such as acetoacetic acidAcetoacetic acidAcetoacetic acid is the organic compound with the formula CH3CCH2CO2H. It is the simplest beta-keto acid group and like other members of this class is unstable.- Synthesis and properties :...
, have the ketone group at the second carbon from the carboxylic acid - Gamma-keto acids, or 4-oxoacids, such as levulinic acidLevulinic acidLevulinic acid, or 4-oxopentanoic acid, is an organic compound with the formula CH3CCH2CH2CO2H. It is a keto acid. This white crystalline is soluble in water, ethanol, and diethyl ether.-Synthesis and uses:...
, have the ketone group at the third carbon from the carboxylic acid.
Amino acids can be deaminated to produce alpha keto acids. Alpha keto acids are used primarily as energy for liver cells and in fatty acid synthesis
Fatty acid synthesis
Fatty acid synthesis is the creation of fatty acids from acetyl-CoA and malonyl-CoA precursors through action of enzymes called fatty acid synthases...
, also in the liver.
Under starvation
Starvation
Starvation is a severe deficiency in caloric energy, nutrient and vitamin intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death...
conditions, stored fats and proteins are the primary means of energy production. Proteins are converted to glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
and Fats can be used to form Ketone bodies
Ketone bodies
Ketone bodies are three water-soluble compounds that are produced as by-products when fatty acids are broken down for energy in the liver and kidney. They are used as a source of energy in the heart and brain. In the brain, they are a vital source of energy during fasting...
. In this situation, proteins are converted to amino acids, which are then converted in the liver to alpha keto acids. The alpha keto acids are then converted by the liver to glucose in a process called gluconeogenesis
Gluconeogenesis
Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
.