Immobilized‐enzyme continuous‐flow reactor incorporating continuous electrochemical regeneration of NAD

Abstract

SummaryElectrochemical regeneration of the cofactor nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) has been coupled with the alcoholdehydrogenation reaction which consumes NAD and produces NADH using alcohol dehydrogenase bound to alumina. Alcohol (reactant) is added directly to the system while aldehyde (product) leaves the system through an ultrafiltration membrane which prevents loss of the cofactor. This system provides a continuous-flow process for carrying out a cofactor-requiring enzymatic reaction with no net loss or consumption of enzyme or cofactor and without the use of reagents for regenerating the cofactor. Although the process shown here is not economically practical, it may be a harbinger of useful and technically feasible chemical reaction systems based on immobilized enzymes requiring cofactors.

H2-Driven biocatalytic hydrogenation in continuous flow using enzyme-modified carbon nanotube columns

“…These issues have hindered implementation of biocatalysis in flow reactors. Electrochemical enzymatic cofactor recycling has been reported for biocatalytic dehydrogenations and hydrogenations, 5,6 but translation of electrocatalytic processes into flow has suffered from complicated reactor designs 7 or low conversion efficiencies (due to the sluggish kinetics of NAD + /NADH cycling at conventional electrodes). 8 We have previously reported a novel approach in which an enzyme cascade for H 2 -driven NADH recycling and a selective NADH-dependent biotransformation is immobilised on carbon particles.…”

Preparation of immobilized baker's-yeast glucose 6-phosphate dehydrogenase attached to modified sepharose and sephadex and a comparison of the properties of these preparations with those of the soluble enzyme

“…There are good reasons for considering that soluble enzymes may be replaced by immobilized enzymes for many of their present applications (Barker & Kay, 1975). Nearly all of these processes use extracellular hydrolases, but recently more consideration has been given to the possibility of using the more expensive intracellular enzymes, which frequently require organic cofactors (Mosbach & Mattiasson, 1970;Marshall, 1973;Hornby et al, 1974;Coughlin et al, 1975;Fink & Rodwell, 1975;Wykes et al, 1975).…”

Mimetic Membrane for Biosensors

“…The electrochemical oxidation of NADH to the corresponding oxidized form NAD þ in aqueous solution has been widely studied. Direct oxidation of NADH at a bare electrode proceeds only at high overpotentials, which finally leads to fouling of the electrode surface (Coughlin et al 1995).…”