decarboxylatio

Decarboxylatio, commonly spelled decarboxylation, is the chemical process by which a carboxyl group (-COOH) is removed from a molecule as carbon dioxide (CO2). The reaction reduces the carbon skeleton by one carbon atom and is widespread in organic chemistry and biochemistry. Decarboxylation can occur nonenzymatically under heat or acidic conditions, but it is also carried out by specialized enzymes known as decarboxylases, often requiring cofactors such as pyridoxal phosphate (PLP) or thiamine pyrophosphate (TPP).

In biology, enzymatic decarboxylations contribute to energy production, metabolism, and biosynthesis. Notable examples include the decarboxylation steps of central carbon metabolism: isocitrate is converted to alpha-ketoglutarate and then to succinyl-CoA with CO2 release in the citric acid cycle, and pyruvate is decarboxylated to acetyl-CoA with CO2 and NADH in the pyruvate dehydrogenase reaction. In amino acid metabolism, decarboxylases remove carboxyl groups from amino acids such as glutamate, producing bioactive amines (for instance, glutamate to GABA) and releasing CO2. These reactions help regulate metabolic flux and end-product formation.

Nonenzymatic, or chemical, decarboxylation occurs when carboxylic acids lose CO2 upon heating or under certain catalytic conditions. For example, malonic acid decarboxylates to acetic acid with CO2 release. In organic synthesis, decarboxylation is a common strategy to remove carboxyl groups or to enable decarboxylative coupling reactions, often used in preparation and labeling methods.

See also: decarboxylation in metabolism; decarboxylase enzymes.