Amination of Ketones by Employing Two New (S)-Selective ω-Transaminases and the His-Tagged ω-TA from Vibrio fluvialis

Two recently identified (S)-selective ?-transaminases (?-TAs) that originate from Paracoccus denitrificans (Strep-PD-?TA, cloned with an N-terminal Strep-tag II) and Pseudomonas fluorescens (PF-?TA) were employed for the asymmetric amination of selected prochiral ketones. The substrates tested were transformed into optically pure amines (>99?% ee) with high conversion (up to >99?%). The ?-TAs led to higher conversion in the absence of dimethyl sulfoxide as a cosolvent than in its presence (15?%, v/v). Additionally, it was shown that a His-tagged recombinant transaminase from Vibrio fluvialis (His-VF-?TA, cloned with an N-terminal His6-tag) showed for a single substrate, ethyl acetoacetate, significantly higher stereoselectivity for the amination compared to the corresponding commercial enzyme preparation (>99 vs. 50?%).