title: Interaction between thymine dimer and flavin-adenine dinucleotide: a DFT and direct ab initio molecular dynamics study.
abstract: The interaction between the fully reduced flavin-adenine dinucleotide (FADH (-)) and thymine dimer (T) 2 has been investigated by means of density functional theory (DFT) calculations. The charges of FADH (-) and (T) 2 were calculated to be -0.9 and -0.1, respectively, at the ground state. By photoirradiation, an electron transfer occurred from FADH (-) to (T) 2 at the first excited state. Next, the reaction dynamics of electron capture of (T) 2 have been investigated by means of the direct ab initio molecular dynamics (MD) method (HF/3-21G(d) and B3LYP/6-31G(d) levels) in order to elucidate the mechanism of the repair process of thymine dimer caused by the photoenzyme. The thymine dimer has two C-C single bonds between thymine rings (C 5-C 5' and C 6-C 6' bonds) at the neutral state, which is expressed by (T) 2. After the electron capture of (T) 2, the C 5-C 5' bond was gradually elongated and then it was preferentially broken. The time scale of the C-C bond breaking and formation of the intermediate with a single bond (T) 2 (-) was estimated to be 100-150 fs. The present calculations confirmed that the repair reaction of thymine dimer takes place efficiently via an electron-transfer process from the FADH (-) enzyme.
authors.affiliation: Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan. hiroto@eng.hokudai.ac.jp
authors.forename: Hiroto
authors.initials: H
authors.lastname: Tachikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawabata
mesh_terms: D000465:Algorithms; D004260:DNA Repair; D004583:Electrons; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D011740:Pyrimidine Dimers / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D011740:Pyrimidine Dimers; D005182:Flavin-Adenine Dinucleotide