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IBEC Seminar: Fernando López-Gallego
Wednesday, April 4, 2018 @ 12:00 pm–1:00 pm
Immobilization of multi-enzyme systems; an avenue to fabricate self-sufficient heterogeneous biocatalysts
Fernando López-Gallego, Heterogeneous Biocatalysis Lab, University of Zaragoza (iQSCH-CSIC) / ARAID, Science Foundation of AragónIn the last decade, the chemists have been delighted by the catalytic orchestration found in vivo, and have isolated multi-enzyme system to work ex-vivo in both natural and non-natural tandem reactions creating a new concept: systems biocatalysis. These systems are the pioneers of the cell-free synthetic biology; an emerging discipline that seeks the simplest biology to make the most complex chemistry. We have paid our attention to the heterogenization of multi-enzyme system to catalyze tandem reactions. Co-immobilization of multi-enzyme systems improve: 1) the kinetics of the chemical cascades due to the spatial localization of the different biocatalytic modules that avoids intermediate accumulation and increases cofactor recycling efficiency, 2) the stability of the biocatalysts due to both structural rigidification and in situ elimination of toxic by-products, 3) the biocatalyst recycle and 4) the biocatalyst adaptation to continuous processes. Nevertheless, the co-immobilization of several enzymes to carry out synthetic cascades is challenging because there is no a universal immobilization chemistry that optimally attaches all the enzymes to the same surface. We have recently developed different immobilized multi-enzyme systems formed by a 3-enzyme cascade for oxidizing phenol derivatives with in situ H2O2 supply, a 3-enzyme cascade for synthesizing 1,3-dihydroxyacetone with both in situ cofactor recycling and H2O2 elimination, a 4-enzyme cascade for quantitatively synthesizing pro-chiral ketones starting from racemic esters and a 2-enzyme cascades to synthesize optically pure secondary alcohols integrating the cofactor recycling in the solid-phase. The optimal design of the immobilization protocols enables co-immobilizing several enzymes and cofactors on the porous carrier to optimize their spatial localization across the carrier microstructure and preserve both global activity and stability of the multi-enzyme systems.
