Ab initio study on the structure and splitting of the uracil dimer anion radical

Alexander A. Voityuk, Notker Rösch

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

As a model for the splitting of pyrimidine base pair defects by DNA photolyase, the uracil dimer and its anion radical have been studied by ab initio HF and MP2 methods. A transition state and an intermediate of the uracil dimer anion radical cleavage reaction have been located. The activation barrier for breaking the C5-C5′ bond in the dimer is found to be 6.2 kcal/mol at the UHF level. However, an MP2 single-point energy evaluation shows a vanishing barrier. The overall reaction energy for the dimer splitting is not sienificantlv affected by electron attachment to the neutral dimer. In the dimer anion radical, the transition state and the intermediate, the two pyrimidine rings differ substantially in their electronic and geometric structure A one-step mechanism is proposed for the dimer splitting in the DNA photorepair process.

Original languageEnglish
Pages (from-to)8335-8338
Number of pages4
JournalJournal of Physical Chemistry A
Volume101
Issue number44
DOIs
StatePublished - 30 Oct 1997

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