AI Article Synopsis
- DNA photolyase utilizes visible light and the reduced flavin cofactor FADH(-) to repair UV-induced DNA damage, specifically cyclobutane pyrimidine dimers (CPDs).
- The repair process involves rapid electron transfer events occurring in about 1 nanosecond, although intermediates involving DNA have not been distinctly observed yet.
- A separate process called photoactivation transforms the inactive flavin radical FADH° back to FADH(-) through electron hopping along a chain of tryptophan residues, taking approximately 30 picoseconds; this tryptophan chain is also present in cryptochrome blue-light photoreceptors.
Article Abstract
DNA photolyase uses visible light and a fully reduced flavin cofactor FADH(-) to repair major UV-induced lesions in DNA, the cyclobutane pyrimidine dimers (CPDs). Electron transfer from photoexcited FADH(-) to CPD, splitting of the two intradimer bonds, and back electron transfer to the transiently formed flavin radical FADH° occur in overall 1ns. Whereas the kinetics of FADH° was resolved, the DNA-based intermediates escaped unambiguous detection yet. Another light reaction, named photoactivation, reduces catalytically inactive FADH° to FADH(-) without implication of DNA. It involves electron hopping along a chain of three tryptophan residues in 30ps, as elucidated in detail by transient absorption spectroscopy. The same triple tryptophan chain is found in cryptochrome blue-light photoreceptors and may be involved in their primary photoreaction.
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| http://dx.doi.org/10.1016/j.sbi.2010.07.003 | DOI Listing |
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