Enzyme-modified particles for selective biocatalytic hydrogenation by hydrogen-driven NADH recycling

Abstract

We describe a new approach to selective H-2-driven hydrogenation that exploits a sequence of enzymes immobilised on carbon particles. We used a catalyst system that comprised alcohol dehydrogenase, hydrogenase and an NAD(+) reductase on carbon black to demonstrate a greater than 98% conversion of acetophenone to phenylethanol. Oxidation of H-2 by the hydrogenase provides electrons through the carbon for NAD(+) reduction to recycle the NADH cofactor required by the alcohol dehydrogenase. This biocatalytic system operates over the pH range 6-8 or in un-buffered water, and can function at low concentrations of the cofactor (10m NAD(+)) and at H-2 partial pressures below 1bar. Total turnover numbers >130000 during acetophenone reduction indicate high enzyme stability, and the immobilised enzymes can be recovered by a simple centrifugation step and re-used several times. This offers a route to convenient, atom-efficient operation of NADH-dependent oxidoreductases for selective hydrogenation catalysis.EC/FP7/258600/EU/Understanding and Exploiting Biological Catalysts for Energy Cycling: Development of Infrared Spectroelectrochemistry for Studying Intermediates in Metalloenzyme Catalysis/EnergyBioCatalysisEC/FP7/297503/EU/Modular beads for regeneration of bio-cofactors in enzyme-catalysed synthesis/HydRegenDFG, EXC 314, Unifying Concepts in Catalysi