Immobilization of ω-transaminases by encapsulation in a sol-gel/celite matrix
ABSTRACT 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).
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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 networkCommunications and Vehicular Technology, 2000. SCVT-200. Symposium on; 02/2000
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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 · 7.65 Impact Factor
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ABSTRACT: A benzoic acid rare earth (Tb) complex was synthesized and characterized. The excitation and emission spectra of the complex were investigated, and then pure organic complex was incorporated with inorganic matrices (SiO2) through sol-gel method. The composition and structure of the hybrid complex was characterized through the IR spectra, TG, TEM and fluorescent spectrometer. Furthermore, the polypropylene (PP) fluorescent fiber with the organic-inorganic hybrid was prepared by melt spinning. The fluorescent and mechanical properties of the fiber were also tested. The results showed that after sol-gel coating the average particulate dimension of the hybrid rare earth complex was less than 100 nm and thermal stability was improved. Meanwhile, the fiber possessed excellent fluorescent and mechanical properties, which could be used as a candidate applied to excellent fluorescent anti-counterfeiting fiber.Journal of Rare Earths 12/2010; 28:211-214. DOI:10.1016/S1002-0721(10)60289-X · 1.34 Impact Factor