Electrochemical behavior and nitric oxide interaction of immobilized cytochrome c ' from Rhodocyclus gelatinosus

Cytochrome c' from Rhodocyclus gelatinosus was immobilized at a mercaptosuc cinic acid modified gold electrode for the first time and the electrochemic al behavior was characterized. The conditions of protein adsorption were in vestigated. Buffer and pH variations indicated a mainly nonionic nature of interaction The heterogeneous electron transfer rate constant of the immobi lized protein was determined (k(s) = 30 s(-1)). The adsorption was found to be stable in protein-free solution for about one week. The immobilized cyt ochrome c' was accessible for nitric oxide molecules in solution. The inter action resulted in an enhanced reduction current in the cyclic voltammogram . When polarized at - 220 mV (cs. Ag/AgCl) the electrode current showed a l inear dependence upon NO concentration. The signal was proven to be sensiti ve within the nanomolar range.