Crystal structures of complexes of the branched-chain aminotransferase from Deinococcus radiodurans with α-ketoisocaproate and L-glutamate suggest the radiation resistance of this enzyme for catalysis.

Branched-chain aminotransferases (BCAT), which utilize pyridoxal 5'-phosphate (PLP) as a cofactor, reversibly catalyze the transfer of the α-amino groups of three of the most hydrophobic branched-chain amino acids (BCAA), leucine, isoleucine, and valine, to α-ketoglutarate to form the respective branched-chain α-keto acids and glutamate. The BCAT from Deinococcus radiodurans (DrBCAT), an extremophile, was cloned and expressed in Escherichia coli for structure and functional studies. The crystal structures of the native DrBCAT with PLP and its complexes with L-glutamate and α-ketoisocaproate (KIC), respectively, have been determined.

Purification, crystallization and preliminary X-ray crystallographic analysis of branched-chain aminotransferase from Deinococcus radiodurans.

The branched-chain amino-acid aminotransferase (BCAT), which requires pyridoxal 5'-phosphate (PLP) as a cofactor, is a key enzyme in the biosynthetic pathway of the hydrophobic amino acids leucine, isoleucine and valine. DrBCAT from Deinococcus radiodurans, which has a molecular weight of 40.9 kDa, was crystallized using the hanging-drop vapour-diffusion method.