PHOTOENZYMIC REPAIR OF UV-DAMAGED DNA - A CHEMISTS PERSPECTIVE

The light utilising DNA repair enzyme known as DNA photolyase induces the reversion of cyclobutane-type pyrimidine dimers in DNA back to pyrimidines thus restoring the DNA function. Either by direct excitation or energy transfer, a noncovalently bound flavin cofactor becomes a powerful reducing agent. Electron transfer to the pyrimidine dimer produces an unstable radical anion and thereby initiates bond cleavage in the dimer. The substrate binding, dimer splitting mechanism, and energetics of the individual steps constitute a fascinating picture of photoenzymic repair of UV damaged DNA.