Voltammetry of dehaloperoxidase on self-assembled monolayers: Reversible adsorptive immobilization of a globin

Dehaloperoxidase (DHP), a monomeric hemoglobin, was adsorptively immobilized under low ionic strength conditions on binary self-assembled monolayers composed of OH- and COOH-terminated alkylthiols. Voltammetry of its Fe(III)/Fe(II) reactions revealed adsorbed DHP to be electroactive and native under both anaerobic and aerobic conditions. The chemically reversible nature of the adsorptive immobilization was established from voltammetric desorption/re-adsorption experiments. Cyclic voltammetric determination of electroactive surface concentration uncovered an unusual inverse scan rate dependence that was rationalized by means of Hoffman's dynamic docking electron transfer model [Z.-X. Liang et al., J. Am. Chem. Soc. 126 (2004) 2785]. This result represents the first evidence for dynamic docking control of protein electron transfer in an electrochemical setting.

► Dehaloperoxidase, a hemoglobin, was adsorptively immobilized on COOH/OH mixed SAMs. ► Adsorption occurred through electrostatic binding and was chemically reversible. ► Ferric/ferrous and ferric/oxyferrous reactions were characterized by CV. ► Voltammetry was interpreted using a dynamic protein docking model.