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PublicationChemCatChem, .
Year2012
Volume4 (9)
Pages1279-1288
International

Rational co-immobilization of bi-enzyme cascades on porous supports and their applications in bio-redox reactions with insitu recycling of soluble cofactors

Authors:PUBLICACIONES
Groups of research:Enzymatic Engineering
In bio-redox cascade reactions that are immobilized on porous supports, mass-transfer limitations may impede the effective concentration of the cofactor around the corresponding dehydrogenases. This main drawback has been addressed by the co-immobilization of both the main and recycling dehydrogenases. Herein, we report tailor-made co-immobilization procedures to assemble three different bio-redox orthogonal cascades invitro (two selective reductions and one selective oxidation) with insitu cofactor-regeneration. However, the co-immobilization itself does not guarantee the success of the biotransformation because the same co-immobilization chemistry may not be suitable for the two enzymes that are involved in the bio-redox cascade. Therefore, our co-immobilization system was optimized for each bi-enzymatic cascade. In all cases, the optimized co-immobilization procedure was more efficient in the biocatalytic cascade than if the two dehydrogenases were immobilized on two different carriers. In one specific case (one thermophilic cascade), the co-immobilization of an optimal ratio of main/recycling dehydrogenases (1:5) on the same carrier resulted in a biocatalyst that was able to recycle NADH up to 9000times per equivalent of substrate in 1hour at 55°C. Moreover, uniform distributions of both dehydrogenases across the porous surface also enhanced the recycling efficiency of the cofactor 1.5-fold versus cascades in which the enzymes were not uniformly distributed across the same porous surface, presumably because of vicinal cooperation effects. Hence, this system for the co-immobilization of bi-enzymatic systems may be extended to other biocatalytic cascades, thereby opening a window for the optimization of other multi-enzyme biotransformations in which cofactor-recycling is necessary. 
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