Histidine Modified Electrode and Its Application to the Electrochemical Studies of Hemeproteins

Abstract

Histidine can be immobilized on a silver electrode surface via a reaction between the substrate metal and the imidazole group of the amino acid. Such a modified electrode is not only electroactive, stable and long-lived, but also can facilitate both the oxidation and reduction of myoglobin and cytochrome c. Experimental results revealed that the modified electrode itself yielded a pair of redox waves in 0.20 mol/L NaAc-HAc buffer (pH 5.5). These anodic and cathodic peaks were at about 0.28 V and 0.06 V (vs. SCE), respectively. The addition of the biological macromolecules myoglobin or cytochrome c to the buffer solution did not cause any new redox peaks, but the intensity of the existing pair of anodic and cathodic peaks clearly increased after either of the biological compounds was added. Since the modifier material, histidine, is an important biomolecule, an interesting modified electrode for bioelectrochemistry is reported here.