Electrochemical reduction of immobilized NADP+ on a polymer modified electrode with a co-polymerized mediator

An electrode chemically modified by the amino group (Polyaminoaniline, PAA) was prepared and the immobilization of the co-polymerized viologen (Alg-V) and of NADP+ on the electrode, was investigated. NADP+ can not be reduced electrocatalytically on the viologen immobilized PAA-modified electrode. On the other hand, a cathodic peak in the cyclic voltammogram of the NADP+ immobilized PAA-modified electrode appeared at −1.2 V vs. SCE. corresponding to the reduction wave of free NADP+ on the electrode. The anodic wave of NADP dimer was not observed in the presence of Alg-V and ferredoxin NADP+ reductase (FRD). A conjugated reaction, coupling the electrochemical regeneration of NADPH on the electrode and a glutathione reductase reaction was performed using Alg-V, FRD, and oxidized form of glutathione. The conjugated redox reaction was successful with the NADP+ immobilized PAA-modified electrode. Under given conditions, the conversion ratio of reduced glutathione (GSH) from oxidized glutathione (GSSG) reached 100% after 2.0 h of incubation at 37°C and the concentration of GSH accumulated in the reaction mixture was 1.0 mM.