Characterization of a (R)-selective amine transaminase from Fusarium oxysporum

Abstract

Abstract Amine transaminases are prominent biocatalysts in the production of chiral amines which are indispensable building blocks in asymmetric synthesis. In this study, a new ( R )-enantioselective amine transaminase from Fusarium oxysporum (ATFo) was identified by genome mining. ATFo possibly evolved from a branched chain amino acid aminotransferase (BCAT) with key amino acids being changed, which belong to one of the three groups of pyridoxal 5′-phosphate dependent enzymes class IV (PLPDE_IV). The gene of the amine transaminase was functionally expressed and the protein was then purified with a molecular mass of approximately 36 kDa. The purified ATFo demonstrated high stereoselectivity towards ( R )-enantiomer of α-phenethylamine and other analogues, which clearly indicated its ( R )-selectivity. The optimal temperature and pH for the activities of ATFo were 25 °C and 7.0, respectively. Addition of Mn 2+ and Zn 2+ could greatly enhance the enzyme activity. In addition, the specific activities and stereoselectivities of these ATFo toward various amino donors and amino acceptors were determined. Compared to ( S )-selective amine transaminase, the ( R )-selective counterpart has been less studied. Given their pivotal role in asymmetric biocatalysis, it is of great importance to find more ( R )-selective amine transaminases with ability or potential for synthesis of the target compounds. Thus, the discovery of the ( R )-selective amine transaminase ATFo is a valuable contribution to the currently small toolbox of these enzymes.