title: Computational study of khellin excited states and photobinding to DNA.
abstract: A theoretical investigation of the formation and spectroscopic properties of the furan and pyrone monoadducts between the photosensitizer khellin and DNA base thymine is reported. The thermal reaction pathways involve very high barriers, whereas the excited state surfaces display low barriers in regions leading to the ground state TS structures and potential wells at the ground state TS geometries. Computed UV absorption spectra are interpreted with the support of molecular orbital calculations, and the role of solvent effects on the spectra is discussed. The red-shift in the khellin spectra upon intercalation in DNA is excellently reproduced by the computational methodology, as is the solvent induced spectral shift. The data also provides an explanation to why khellin predominantly forms furan monoadducts in DNA, as opposed to the closely related psoralen compounds.
authors.affiliation: Orebro Life Science Center, School of Science and Technology, Orebro University, 701 82, Orebro, Sweden.
authors.forename: Salama
authors.initials: S
authors.lastname: Omar
authors.forename: Leif A
authors.initials: LA
authors.lastname: Eriksson
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D007666:Khellin / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D013941:Thymine / Q000737:chemistry / Q000378:metabolism
chemical_list: D017319:Photosensitizing Agents; D007666:Khellin; D004247:DNA; D013941:Thymine