Synthesis of Optically Active Amines Employing Recombinant omega-Transaminases in E. coli Cells

Various recombinant (omega-transaminases, overexpressed in E. coli cells and employed as whole-cell catalysts, are tested for the synthesis of enantiomerically pure amines from the corresponding prochiral ketones. Optically pure (S)-amines are obtained by formal reductive amination, consuming just ammonia and a cheap reducing agent (formate) with up to 99% ee and 97% yield. The other enantiomer was accessible by employing the same omega-transaminases in a kinetic resolution starting from racemic amines. A omega-transaminase derived from an Arthrobacter species displayed the highest stereoselectivity for all substrates tested, both for the kinetic resolution of rac-amines and for the amination of ketones.