title: NMR studies of bipyrimidine cyclobutane photodimers.
abstract: Cyclobutane-type photodimers of dinucleoside monophosphates dCpdT, dTpdC and dTpdT were prepared by ultraviolet irradiation in the presence of acetophenone as photosensitizer. The cytosine-containing derivatives were found to deaminate forming uracil products. Using one- and two-dimensional NMR, the photoproducts were characterized as cis-syn and trans-syn cyclobutane photodimers. On the basis of NOE data the structures of the cis-syn and trans-syn products of dUpdT were determined using distance-geometry and restrained-energy-minimization methods. The cis-syn structures showed (high-ANTI/SYN)/high-ANTI glycosidic linkages while the trans-syn structures were in the SYN-ANTI region. The backbone conformations of both structures were in fair agreement with the coupling-constant-data. The trans-syn structures were found to be very rigid and similar in all three products. For the three cis-syn structures more conformational freedom and more variation among the three structures was observed.
authors.affiliation: Department of Chemistry, University of Utrecht, The Netherlands.
authors.forename: M G
authors.initials: MG
authors.lastname: Koning
authors.forename: J J
authors.initials: JJ
authors.lastname: van Soest
authors.forename: R
authors.initials: R
authors.lastname: Kaptein
mesh_terms: D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D011740:Pyrimidine Dimers / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D011740:Pyrimidine Dimers