ELECTROCHEMISTRY OF HEMOGLOBIN AT MODIFIED SILVER ELECTRODES IS NOT AREDOX-PROCESS OF IRON PROTOPORPHYRIN-IX

The direct heterogenous electron transfer between hemoglobin and modif ied silver and gold electrodes has been investigated using cyclic volt ammetry. Cathodic and anodic peak currents have been obtained for hemo globin, methemoglobin, carbonylhemoglobin, cyanohemoglobin and oxyhemo globin, as well as for apohemoglobin and bovine serum albumin, exclusi vely at modified silver electrodes at potentials around 70 and 270 mV (vs. Ag/AgCl). The results demonstrate that the observed redox chemist ry was not a result of direct electron transfer to the redox centre pr otoporphyrin IX. Spectrometrical measurements were made to substantiat e this conclusion. A possible reaction mechanism which takes place at the modified silver electrode is suggested.