Electrochemical characterization of immobilized NAD +

Abstract

Nicotinamide adenine dinucleotide (NAD +) has been covalently attached to alginic acid using carbodiimide coupling, thereby producing a macromolecular adduct of NAD, which can be rendered either soluble or insoluble by adjustment of pH. It was found that this NAD + · alginic acid complex was enzymatically active, and also that the oxidized form could be electrochemically reduced without loss in enzymatic activity. This NAD + adduct has now also been polarographically characterized as to its two-step reduction waves, which are slightly shifted toward more cathodic potential as compared to free NAD +. When controlled electrolysis was conducted to reduce the bound NAD + at the cathode, the NADH so formed by electrochemical action was found to be again oxidizable either enzymatically or electrochemically without loss in co-enzymic function. The NADH adduct produced by electrochemical reduction of the NAD + adduct has also been characterized by voltammetry.