Electrocatalysis of nitric oxide reduction by hemoglobin entrapped in surfactant films

We have investigated the electrochemical reduction of NO catalyzed by hemoglobin, HbFe, trapped within a dimethyldidodecylammonium bromide (DDAB) film cast on a glassy carbon electrode. The presence of NO in the electrolyte drastically changes the voltammetric response of the DDAB/HbFe film. Two reduction waves, with intensity proportional to NO concentration, are observed at -0.6 and -1.0 V versus SCE, respectively. The reduction wave at -1.0 V is a mass-transport controlled one. The typical voltammetric behavior of HbFe is discussed in terms of reactivity of the iron-heme enzyme toward NO, giving ferrous nitrosyl and nitroxyl adducts.