The structure to the right of branched chain amino acid aminotransferase was found using X-ray diffraction with a resolution of 2.20 Å.

In addition to the Schiff base linkage, PLP is anchored to the active site of the enzyme via hydrogen bonding at the Tyr 207 and Glu237 residues.

[5] Mammalian BCATs show a unique structural CXXC motif (Cys315 and Cys318) sensitive to oxidizing agents[7] and modulated through S-nitrosation,[8] a post-translational modification that regulates cell signaling.

[9] Modification of these two cysteine residues via oxidation (in vivo/vitro) or titration (in vitro) has been found to inhibit enzyme activity,[4] indicating that the CXXC motif is crucial to optimal protein folding and function.

[11] Although the CXXC motif is present only in mammalian BCATs, the surrounding amino acid residues were found to be highly conserved in both prokaryotic and eukaryotic cells.

Cytosolic branched-chain amino acid aminotransferases are the less common of the two isoforms, found in the cytoplasm of mammalian cells almost exclusively throughout the nervous system.

[11] Human BCATc is encoded by BCAT1[18] Mitochondrial branched-chain amino acid aminotransferases are the more ubiquitous of the two isoforms, present in all tissues in the mitochondria of the cell.

[23] However, studies of BCATs in Solanum tuberosum (potato) revealed two isoforms that are 683 (BCAT1) and 746 (BCAT2) bp long located primarily in chloroplasts.

[26] Because branched chain amino acids are crucial in the formation and function of many proteins, BCATs have many responsibilities in mammalian physiology.

[27] In the brain, BCATc regulates the amount of glutamate production for use as a neurotransmitter or for future γ-Aminobutyric acid (GABA) synthesis.

[30] In bacterial physiology, BCATs perform both reactions, forming both α-ketoacids and branched chain amino acids.

[31] In Streptococcus mutans, the gram-positive bacteria that lives in human oral cavities and is responsible for tooth decay, amino acid biosynthesis/degradation has been found to regulate glycolysis and maintain the internal pH of the cell.

Aminotransferases (transaminases) in general have been used to create unnatural amino acids, important building blocks for peptidomimetic drugs and agricultural products.

[41] Along with the aromatic aminotransferases (AraT), BCATs in L. lactis help develop the aroma/flavor resulting from volatile sulphur compounds produced during fermentation.

The bacteria Staphylococcus carnosus and Enterococcus faecalis are often used in tandem with other lactic acid bacterium to begin the meat fermentation process.

As fermentation proceeds, these α-ketoacids degrade into a class of compounds known as methyl-branched volatiles that include aldehydes, alcohols, and carboxylic acids, all of which contribute to the distinct scents and flavors of cured meats.