Immobilization of ω-transaminases by encapsulation in a sol–gel/celite matrix

Commercially available ω-transaminases ω-TA-117, -113, and Vibrio fluvialis (Vf-AT) have been immobilized in a sol–gel matrix. Improved results were obtained by employing Celite 545 as additive. The immobilized ω-transaminases ω-TA-117, -113, and V. fluvialis (Vf-AT) were tested in the kinetic resolution of α-chiral primary amines. In contrast to the free enzyme ω-TA-117, the sol–gel/celite immobilized enzyme showed activity even at pH 11. Recycling of the sol–gel/Celite 545 immobilized ω-transaminase ω-TA-117 was performed over five reaction cycles without any substantial loss in enantioselectivity and conversion. Finally, the immobilized ω-TA 117 was employed in a one-pot two-step deracemization of rac-mexiletine and rac-4-phenyl-2-butylamine, two pharmacologically relevant amines. The corresponding optically pure (S)-amines were obtained in up to 95% isolated yield (>99% ee).