Abstract
Thin-layer spectroelectrochemical methods have been employed to measure the reduction potentials of the blue copper in Polyporus versicolor laccase (EC 1.10.3.2) between 7°C and 41°C (0.2 M sodium phosphate, pH 5.4). Thermodynamic parameters are: ΔS° = -13.9 ± 2 cal/mol-K; ΔH° = -22.1 ± 0.5 kcal/mol; E° (25°C) = 780 ± 3 mV vs. the normal hydrogen electrode. Comparison of the ΔS° and ΔH° values with those for single-site proteins suggests that the high potential of the blue copper in fungal laccase is attributable mainly to stabilization of the copper (I) center by enhanced ligand binding interactions and that protein solvation effects play a lesser role.
Keywords: spectroelectrochemistry, thermodynamic parameters
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Selected References
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