Absorption spectroscopy and electron transfer mechanism in proteins

Absorption spectroscopy and electron transfer mechanism in proteins 

Electron will be transferred via the protein matrix and the protein-protein interface. Therefore, one should ask whether the structure and the dynamics of the proteins play an important role in the determination of the rate of this electron transfer or not Also, the relative orientation and distance of the two redox potential centers will have another detemiinant role in the electron transfer efficiency. 

It has been considered that protein dynamics are too slow to affect electron transfer. However, the different kinetic constants measured for the electron transfer for proteins indicates that the electron transfer can occur within the range of the protein dynamics timescale. For example, the highest kinetic constant for the electron transfer between Zn porphyrin to Ruthenium both bound to myoglobin is found equal to 7.2 x 10 s (Casimiro et al. 1993.) This means a time equal to 14 ns. This time is in the same range of the protein rotation and even slower from the time of the local rotation which averages 1 ns or less. 

Unlike adiabatic diemical reactions, electron transfer mechanism does not affect the molecule bonds of the concerned materials. I be kinetic constant of electron transfer can be writtoi as 4aicus and Sutin,. 1985)  

A G + / 4 is the activation free energy, A G is the driving force of the redox 

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