In situ NAD + regeneration using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) as an electron transfer mediator

Abstract

Electrochemical oxidation of reduced nicotinamide adenine dinucleotide (NADH) proceeds very effectively at 0.585 V versus Ag ∣ AgCl in pH 9.0 buffered solution at ambient temperature using ABTS 2− (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) as an electron transfer mediator. The electrochemistry of ABTS 2− and its oxidized form ABTS − , as well as the coupled homogeneous reactions were studied, and the rate constants were estimated using cyclic voltammetry and photometric methods ( k app,NADH=5.6–6.45×10 3 M −1 s −1). The mediated electrochemical oxidation was successfully coupled to horse liver alcohol dehydrogenase catalyzed oxidation of a meso-diol to a chiral lactone (yield 93.5%, ee>99.5%).