Electron-transfer reactions in proteins: electronic coupling in myoglobin

Abstract

Recent measurements of electron-transfer (ET) rates in Ru(NH_3)_5 His myoglobin derivatives have shown the
\nneed for improved theories for treating the "path" of long-range ET. We have investigated these systems
\ntheoretically using a combined artificial intelligence (AI)-superexchange method. As in our previous articles,
\nthis model first employs an AI search technique that yields the important amino acid residues for the mediation
\nof electrons between the donor and the acceptor. A quantum mechanical method is then used to diagonalize
\nthe orbitals of the selected protein subset and to calculate the electronic coupling. Encouraging agreement with
\nexperimental data is found, no adjustable parameters having been introduced. The results yield the relevant
\namino acid paths.