Pathways of electron transfer in Escherichia coli DNA photolyase: Trp(306)to FADH

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.