transaminated

Transaminated is the past participle or adjective describing a molecule that has undergone transamination, the transfer of an amino group from one molecule to another. The process, called transamination, transfers an amino group from an amino acid to an alpha-keto acid, producing a new pair of amino acid and alpha-keto acid. It is catalyzed by transaminases (aminotransferases), a family of pyridoxal phosphate (PLP)-dependent enzymes. The reaction is usually reversible and occurs in many tissues, especially the liver and muscle in animals, and is central to nitrogen metabolism and amino acid biosynthesis.

In classic metabolism, two well-known examples are alanine transaminase (ALT) and aspartate transaminase (AST). ALT catalyzes alanine + alpha-ketoglutarate ⇌ pyruvate + glutamate; AST catalyzes aspartate + alpha-ketoglutarate ⇌ oxaloacetate + glutamate. The general mechanism involves PLP forming a Schiff base with the amino acid, transferring the amino group to the cofactor, and then to the alpha-keto acid, regenerating the enzyme and PLP.

Biologically, transamination allows interconversion of amino acids and the production of Krebs cycle intermediates, linking nitrogen metabolism with energy metabolism and gluconeogenesis. Clinically, measurements of AST and ALT in blood are common indicators of liver injury, though levels can rise in other conditions affecting muscle or heart.

Transaminated compounds are common in biosynthetic pathways and can be engineered for amino acid production, metabolic tracing, or label incorporation in research. The term is used to describe an amino acid that has served as an amino donor or recipient in a transamination reaction.