Direct observation of DNA repair by photolyase

This chapter reports a direct observation of pyrimidine dimer repair in DNA by photolyase. With femtosecond resolution, the photocycle is followed in real time through mapping out the temporal evolution of entire catalytic reactions. Direct observation of the intermediate of a fully reduced deprotonated flavin radical proves the electron-transfer radical mechanism. Active-site solvation is observed to occur on picosecond-to-nanosecond time scales and to play a critical role by the continuous modulation of catalytic reactions. These synergistic motions in the active site of the damaged DNA-enzyme complex, optimized by evolution, revealed a perfect correlation of structural integrity and dynamical locality to ensure maximum repair efficiency on the ultrafast time scales. The elementary reactions of energy and electron transfer in DNA repair by photolyase are reported in this contribution.