Thermal Denaturation of Spinach Plastocyanin: Effect of Copper Site Oxidation State and Molecular Oxygen†

摘要: The thermal denaturation of the cupredoxin plastocyanin (PC) from spinach has been studied with aim improving understanding factors involved in conformational stability antiparallel β-sheet proteins. Studies using differential scanning calorimetry have complemented nuclear magnetic resonance spectroscopy, absorbance dynamic light scattering, and mass spectrometry elucidation effect copper-site oxidation state on irreversible process. Our results indicate that copper-catalyzed metal-ligating cysteine is sole factor resulting irreversibility. However, this can be prevented reduced protein by removal molecular oxygen. Application a two-state equilibrium transition model to folding process thus allowed extraction thermodynamic parameters for (ΔtrsH = 494 kJ mol-1, ΔHvH 343 Tm 71 °C). anaerobically denatured oxidized protei...