A cyclic voltammetry study of the adsorption of alcohol dehydrogenase (HLADH) onto a platinum electrode

A cyclic voltammetry study of the interfacial behaviour of horse liver alcohol dehydrogenase (HLADH) at a Pt surface in a phosphate buffer solution pH 7.0 over the temperature range 273 to 353 K is presented. The surface charge density, resulting from protein adsorption, was shown to be directly proportional to the amount of adsorbed protein (surface concentration). HLADH exhibits very high affinity towards adsorption onto a Pt surface via chemisorption. The Langmuir isotherm was employed for modeling the adsorption process and the values of the Gibbs free energy, enthalpy and entropy of adsorption were calculated. The thermodynamic data suggested that disruption of tertiary structure of the protein occurs upon adsorption at the Pt surface and that the breaking of intramolecular interactions during the adsorption governs the rate of the process.