title: Monte Carlo simulation of radiolytic attack to 5'-d[T4G4]4 sequence in a unimolecular quadruplex.
abstract: OBJECTIVE
  To extend to a quadruplex the stochastic model of radiolytic attack previously applied to a quasi-random duplex DNA.
  
  
  METHODS
  The quadruplex structure is obtained from the PDB databank (first structure from 201D entry). The probabilities of OH* radical attack at all sugar and base reaction sites are calculated using a stochastic model based on the Monte Carlo method.
  
  
  RESULTS
  Good agreement between the calculated and experimental frank strand break (FSB) probabilities is obtained using the relative efficiencies of conversion of the C4' and C5'-centred radicals into FSB determined for the quasi-random duplex (2.8:1 respectively). Efficiencies of base radicals-to-alkali-revealed breaks (ARB) conversion are determined by fitting the calculated probabilities of base attack to the previously reported experimental probabilities for ARB. The efficiency of conversion of thymine radical into an ARB is 3.4+/-0.7 times higher than for guanine radical.
  
  
  CONCLUSIONS
  This paper supports the calculation method and allows evaluation of the relative efficiencies of thymine and guanine radicals-to-ARB conversion.
authors.affiliation: Centre de Biophysique Moléculaire, CNRS, Orléans, France.
authors.forename: M
authors.initials: M
authors.lastname: Begusova
authors.forename: L
authors.initials: L
authors.lastname: Tartier
authors.forename: D
authors.initials: D
authors.lastname: Sy
authors.forename: M
authors.initials: M
authors.lastname: Spotheim-Maurizot
authors.forename: V
authors.initials: V
authors.lastname: Michalik
authors.forename: M
authors.initials: M
authors.lastname: Charlier
authors.forename: D
authors.initials: D
authors.lastname: Syt
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000528:radiation effects*; D004249:DNA Damage; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects; D066298:In Vitro Techniques; D008956:Models, Chemical; D009010:Monte Carlo Method; D009690:Nucleic Acid Conformation / Q000528:radiation effects; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000528:radiation effects*; D013269:Stochastic Processes
chemical_list: D005609:Free Radicals; D009838:Oligodeoxyribonucleotides; D004247:DNA