We describe the results of a series of theoretical calculations of electron
transfer pathways between Trp(306) and *FADH(.) in the Escherichia coli DN
A photolyase molecule, using the method of interatomic tunneling currents.
It is found that there are two conformationally orthogonal tryptophans, Trp
(359) and Trp(382), between donor and acceptor that play a crucial role in
the pathways of the electron transfer process. The pathways depend vitally
on the aromaticity of tryptophans and the flavin molecule. The results of t
his calculation suggest that the major pathway of the electron transfer is
due to a set of overlapping orthogonal pi-rings, which starts from the dono
r Trp(306), runs through Trp(359) and Trp(382), and finally reaches the fla
vin group of the acceptor complex, FADH.