ELECTRON-TRANSFER REACTIONS IN PROTEINS - ELECTRONIC COUPLING IN MYOGLOBIN

Recent measurements of electron-transfer (ET) rates in Ru(NH3)5 His my oglobin derivatives have shown the need for improved theories for trea ting the ''path'' of long-range ET. We have investigated these systems theoretically using a combined artificial intelligence (AI)-superexch ange method. As in our previous articles, this model first employs an AI search technique that yields the important amino acid residues for the mediation of electrons between the donor and the acceptor. A quant um mechanical method is then used to diagonalize the orbitals of the s elected protein subset and to calculate the electronic coupling. Encou raging agreement with experimental data is found, no adjustable parame ters having been introduced. The results yield the relevant amino acid paths.