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 pyr imidines thus restoring the DNA function. Either by direct excitation or energy transfer, a noncovalently bound flavin cofactor becomes a po werful reducing agent. Electron transfer to the pyrimidine dimer produ ces an unstable radical anion and thereby initiates bond cleavage in t he dimer. The substrate binding, dimer splitting mechanism, and energe tics of the individual steps constitute a fascinating picture of photo enzymic repair of UV damaged DNA.