Electron tunneling between molecules attached to proteins

Electron tunneling between molecules attached to proteins 

There are several requirements for an ideal protein system for such studies [68-70]. First, in order to facilitate structure vs. function comparisons, the proteins studied should be of known structure. This structure may be obtained, for example, by high-resolution X-ray spectroscopy. Second, physiological redox protein couples are preferred, since such systems are more likely to provide information on biological design than studies of non-physiological redox couples. Third, for practical purposes, it is 

4 Electron Tunneling Between Molecules Attached to Proteins 

Protein matrices are believed to play an important role in the accomplishment of photochemical electron transfer reactions in biological systems. First, the fragments 

In order to utilize photochemical electron transfer, investigators have replaced the Fe-containing porphyrin active sites in several redox proteins with equivalent photoactive porphyrins. 

The system then returns to its initial state by back electron transfer from Fe(II)P to (ZnP)+. The decay of the TZnP triplet state is enhanced only when the P subunit contains Fe(III)P. When the p subunit contains Fe(II)P, the triplet state is unaffected. The rate constant of electron transfer, k for [a(Zn)p(Fe)] hybrid hemoglobin was found to be 102 s 1 at room temperature [265]. The same value of k, was obtained for [oc(Fe) P(Zn)] hybrid hemoglobin [264], 

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