Rate constants azurin systems

Direct evidence for long range electron-transfer in biological systems was first observed by Gray et al.50,51) and Isied et al.481 using [Ru(NH3)5]3+ substituted metallo protein. Histidine-83 of blue copper (azurin) was labeled with Ru(III)(NH3)5 50). Flash photolysis reduction of the His-83 bound Ru(III) followed by electron-transfer from the Ru(II) to Cu2+ was observed with a rate constant of 1.9 s 1. The result shows that intramolecular long distance (approx. 1 nm) electron-transfer from the Ru(II) to the Cu2 + of the azurin takes place rapidly. 

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