Histidine modified electrode and its application to the electrochemical studies of hemeproteins

Histidine can be immobilized on a silver electrode surface via a reaction b etween the substrate metal and the imidazole group of the amino acid. Such a modified electrode is not only electroactive, stable and long-lived but a lso can facilitate both the oxidation and reduction of myoglobin and cytoch rome c. Experimental results revealed that the modified electrode itself yi elded a pair of redox waves in 0.20 mol/L NaAc-HAc buffer (pH 5.5). These a nodic and cathodic peaks were at about 0.28 V and 0.06 V (vs. SCE), respect ively. The addition of the biological macromolecules myoglobin or cytochrom e c to the buffer solution did not cause any new redox peaks, but the inten sity of the existing pair of anodic and cathodic peaks clearly increased af ter either of the biological compounds was added. Since the modifier materi al, histidine, is an important biomolecule, an interesting modified electro de for bioelectrochemistry is reported here.