Collect. Czech. Chem. Commun. 2004, 69, 759-775

Electrochemistry of Dopamine β-Hydroxylase in Adsorbed State at a Gold Electrode

Ana Iona, Torbjørn Ljonesb and Florinel G. Banicab,*

a Department of Analytical Chemistry and Instrumental Analysis, University Politehnica of Bucharest, Romania
b Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway


Dopamine β-hydroxylase (DBH) adsorbed on gold electrode was investigated by electrochemical and quartz crystal microbalance methods. It was found that DBH can adsorb irreversibly on a gold electrode under open circuit conditions. In a neutral phosphate buffer, the adsorbed layer is stable to desorption within the potential range of 0.6 to -0.7 V vs Ag|AgCl (1 M KCl) electrode. At potentials positive than 0.8 V, adsorbed DBH undergoes an electrochemical oxidation involving probably tyrosine, tryptophan and histidine residues. This process is accompanied by DBH desorption and gold oxidation. In the cathodic potential region, from -0.2 to -0.7 V, DBH exhibits two reductions assigned to disulfide groups. No charge transfer reactions involving the copper centres in DBH have been noticed. However, DBH can bind reversibly copper(II) ions, which are not involved in the enzymatic activity and their presence was proved by voltammetry. The compactness of the adsorbed film was checked by cyclic voltammetry of selected redox probes at the DBH-coated electrode.

Keywords: Adsorption; Copper protein; Glycoproteins.

References: 53 live references.