Bifurcating electron-transfer pathways in DNA photolyases determine the repair quantum yield

Abstract

Two roads diverged in a yellow photolyase Photolyase enzymes repair DNA that has been damaged by ultraviolet sunlight. The repair process begins when blue light absorption by a cofactor drives an electron transfer step. Zhang et al. applied ultrafast absorption spectroscopy to study the dynamics of this step. A bifurcation in the electron transfer pathway favors a direct tunneling mechanism in the prokaryotic enzymes and a two-step hopping mechanism in the eukaryotic variety. This difference explains the higher repair quantum yield seen in prokaryotes. Science , this issue p. 209