title: The radical cationic repair pathway of cyclobutane pyrimidine dimer: the effect of sugar-phosphate backbone.
abstract: Radical cationic repair process of cis-syn thymine dimer has been investigated when (1) sugar-phosphate backbones were substituted by hydrogen atoms, (2) phosphate group was substituted by two hydrogen atoms each on a sugar ring and (3) sugar-phosphate backbone was taken into account. The effect of the interactions between N1 and N1' lone pairs and the C6-C6' antibonding orbital are the most important evidences for the cleavage of the C6-C6' bond in the first step of radical cationic repair mechanism in the absence of the sugar-phosphate backbone. The impact of the N1 and N1' lone pairs on the C6-C6' bond cleavage decreases and the energy barrier of the cleavage of that bond significantly increases in the presence of the deoxynucleoside sugars and the sugar-phosphate backbone.
authors: Department of Chemistry, University of Sistan and Baluchestan, Zahedan, Iran. ebrahimi@hamoon.usb.ac.ir
authors: Ali
authors: A
authors: Ebrahimi
authors: Mostafa
authors: M
authors: Habibi-Khorassani
authors: Asiyeh
authors: A
authors: Shahraki
mesh_terms: D002412:Cations; D004260:DNA Repair; D005609:Free Radicals / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D011740:Pyrimidine Dimers / Q000737:chemistry*; D013403:Sugar Phosphates / Q000737:chemistry*; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry*
chemical_list: D002412:Cations; D005609:Free Radicals; D011740:Pyrimidine Dimers; D013403:Sugar Phosphates; D006859:Hydrogen; D013941:Thymine