Transaminases
In biochemistry, a transaminase or an aminotransferase is an enzyme that catalyzes a type of reaction between an amino acid and an α-keto acid. They are important in the synthesis of amino acids, which form proteins. In medicine, they are an important indicator of liver damage.
An amino acid contains an amine (NH2) group. A keto acid contains a keto (=O) group. In transamination, the NH2 group on one molecule is exchanged with the =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid becomes an amino acid.
Some transamination activities of the ribosome have been found to be catalyzed by so-called ribozymes (RNA enzymes). Examples being the hammerhead ribozyme, the VS ribozyme and the hairpin ribozyme.
The transaminase enzymes are important in the production of various amino acids, and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases. Transaminases require the coenzyme pyridoxal-phosphate, which is converted into pyridoxamine in the first phase of the reaction, when an amino acid is converted into a keto acid. Enzyme-bound pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha-ketoglutarate, giving alanine, aspartic acid, or glutamic acid, respectively. Many transamination reactions occur in tissues, catalysed by transaminases specific for a particular amino/keto acid pair. The reactions are readily reversible, the direction being determined by which of the reactants are in excess. The specific enzymes are named from one of the reactant pairs, for example; the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called glutamic-pyruvic transaminase or GPT for short.
...
Wikipedia