Document Detail

A triplet mechanism for the formation of cyclobutane pyrimidine dimers in UV-irradiated DNA.
MedLine Citation:
PMID:  16599537     Owner:  NLM     Status:  MEDLINE    
The reaction pathways for the photochemical formation of cyclobutane thymine dimers in DNA are explored using hybrid density functional theory techniques. It is concluded that the thymine-thymine [2 + 2] cycloaddition displays favorable energy barriers and reaction energies in both the triplet and the singlet excited states. The stepwise cycloaddition in the triplet excited state involves the initial formation of a diradical followed by ring closure via singlet-triplet interaction. The triplet mechanism is thus completely different from the concerted singlet state cycloaddition processes. The key geometric features and electron spin densities are also discussed. Bulk solvation has a major effect by reducing the barriers and increasing the diradical stabilities. The present results provide a rationale for the faster cycloreaction observed in the singlet excited states than in the triplet excited states.
Ru Bo Zhang; Leif A Eriksson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  110     ISSN:  1520-6106     ISO Abbreviation:  J Phys Chem B     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-04-07     Completed Date:  2007-07-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7556-62     Citation Subset:  IM    
Department of Natural Sciences and Orebro Life Science Center, Orebro University, 70182 Orebro, Sweden.
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MeSH Terms
Computer Simulation
Cyclobutanes / chemistry*
DNA / chemistry*,  radiation effects*
Hydrogen Bonding
Models, Molecular
Pyrimidines / chemistry*
Thymine / chemistry
Ultraviolet Rays
Reg. No./Substance:
0/Cyclobutanes; 0/Pyrimidines; 0/Solvents; 65-71-4/Thymine; 9007-49-2/DNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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