Direct observation of thymine dimer repair in DNA by photolyase

Ya-Ting Kao, Chaitanya Saxena, Lijuan Wang, Aziz Sancar*, Dongping Zhong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

206 Scopus citations


Photolyase uses light energy to split UV-induced cyclobutane dimers in damaged DNA, but its molecular mechanism has never been directly revealed. Here, we report the direct mapping of catalytic processes through femtosecond synchronization of the enzymatic dynamics with the repair function. We observed direct electron transfer from the excited flavin cofactor to the dimer in 170 ps and back electron transfer from the repaired thymines in 560 ps. Both reactions are strongly modulated by active-site solvation to achieve maximum repair efficiency. These results show that the photocycle of DNA repair by photolyase is through a radical mechanism and completed on subnanosecond time scale at the dynamic active site, with no net change in the redox state of the flavin cofactor.

Original languageEnglish
Pages (from-to)16128-16132
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number45
StatePublished - 8 Nov 2005


  • Photocycle
  • Radical mechanism
  • Ultrafast kinetics

Fingerprint Dive into the research topics of 'Direct observation of thymine dimer repair in DNA by photolyase'. Together they form a unique fingerprint.

Cite this