Three-Dimensional Structure of Branched-Chain Amino Acid Transaminase from Thermoproteus uzoniensis in Complex with L-Norvaline

Transaminases (aminotransferases) are stereospecific enzymes catalyzing the reversible amino group transfer from various substrates. Transaminases are key enzymes in amino acid metabolism in all organisms, and they show promise for fine organic synthesis. Among a diversity of transaminases, as-yet poorly characterized pyridoxal 5′-phosphate-dependent fold type IV transaminases have attracted great interest. This transaminase family shows specificity for both D- and L-amino acids and (R)-amines. The crystal structure of thermally stable fold type IV branched-chain amino acid transaminase from the archaeon Thermoproteus uzoniensis in complex with the non-natural substrate L-norvaline was established. The mechanism of substrate binding is considered. The key amino acids involved in the substrate binding are described.