Hyperthermophilic redox chemistry: a re-evaluation

The redox chemistry of Pyrococcus furiosus rubredoxin and ferredoxin has be en studied as a function of temperature in direct voltammetry and in EPR mo nitored bulk titrations, The E(m)s of both proteins, measured with direct v oltammetry, have a normal (linear) temperature dependence and show no pH de pendence. EPR monitoring is not a reliable method to determine the temperat ure dependence of the E-m: upon rapid freezing the proteins take their conf ormation corresponding to the freezing point of the solution. (C) 1998 Fede ration of European Biochemical Societies.