LONG-RANGE ELECTRON-TRANSFER IN PROTEINS - A RENORMALIZED-PERTURBATION-EXPANSION APPROACH

An efficient algorithm for calculating the electronic matrix element T(DA) for electron-transfer reactions between a donor D and acceptor A in biological systems is presented. The tight-binding Hamiltonian and the Green's-function formalism are used to obtain T(DA) via the renormalized-perturbation expansion. This procedure permits taking into account the detailed structure of the array provided by the specific protein that assists the electron transfer. As an application, results are presented for the calculation of some of these matrix elements in metal-labeled myoglobin, and comparison with experimental data is made. By analyzing the self-energies at each site of the array, these results can be understood as a small-denominator effect.