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).
[Show abstract][Hide abstract] ABSTRACT: The current demands of the world’s biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. These requirements are inevitable to facilitate large-scale and economic formulation. Enzyme immobilization provides an excellent base for increasing availability of enzyme to the substrate with greater turnover over a considerable period of time. Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Nowadays, immobilized enzymes are preferred over their free counterpart due to their prolonged availability that curtails redundant downstream and purification processes. Future investigations should endeavor at adopting logistic and sensible entrapment techniques along with innovatively modified supports to improve the state of enzyme immobilization and provide new perspectives to the industrial sector.
[Show abstract][Hide abstract] ABSTRACT: This paper addresses the problem of resource allocation in a
general multiple access scenario. Powers are supposed to be fixed and
maximization of the bit rate is put as an objective, with a number of
fairness constraints that provide each user with individual bit rates in
proportion with their needs. Linear programming algorithms give the
solution for the matched filter bound. As soon as the channels are
frequency-selective, the use of joint detectors is proposed. An adapted
allocation algorithm is given, that implies the update of the joint
detector performance for each iteration. A fast update algorithm is also
proposed. Results are given for a 5-user powerline access network
Communications and Vehicular Technology, 2000. SCVT-200. Symposium on; 02/2000
[Show abstract][Hide abstract] ABSTRACT: The combination of an oxidation and a reduction in a cascade allows performing transformations in a very economic and efficient fashion. The challenge is how to combine an oxidation with a reduction in one pot, either by running the two reactions simultaneously or in a stepwise fashion without isolation of intermediates. The broader availability of various redox enzymes nowadays has triggered the recent investigation of various oxidation-reduction cascades.
Current opinion in chemical biology 12/2010; 15(2):249-56. DOI:10.1016/j.cbpa.2010.11.010 · 6.81 Impact Factor
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