Direct electrochemical characterization of the interaction between haemoglobin and nitric oxide

Direct electrochemistry was carried out to investigate the interaction between haemoglobin (Hb) and nitric oxide (NO), employing a Hb–DNA film modified electrode. DNA was used as an electrochemical “promoter” for the direct electron transfer of Hb at the electrode surface. Aside from a pair of peaks corresponding to the redox reaction of Hb, two additional peaks were observed in a solution containing NO. The pre-peak, located at −0.070 V s. SCE, was proposed to come from the chemical redox reaction, i.e., NO-induced oxidation of Hb in the film, coupled electron transfer process of Hb. The other peak, at −0.684 V s. SCE, was assigned to the reduction of heme-ligated NO. These phenomena were proposed to be related to the electron transfer and binding process between Hb and NO.