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Ostrowski, T ; Maurizot, JC ; Adeline, MT ; Fourrey, JL ; Clivio, P

Sugar conformational effects on the photochemistry of thymidylyl(3 ’-5 ’)thymidine

Journal of Organic Chemistry 68 (17) 6502-6510

par Administrateur - publié le

Abstract :

The synthesis and conformational analysis of 2’-O,5-dimethyluridylyl(3’-5’)-2’-O,5-dimethyluridine (1a), the analogue of thymidylyl(3’-5’)thymidine (TpT ; 1b) in which a methoxy group replaces each 2’-a-hydrogen atom, are described. In comparison with TpT, such modification increases the population of the C3’-endo conformer of the sugar ring puckering at the 5’- and 3’-ends from 30 to 75% and from 37 to 66%, respectively. Photolyses of 1a and TpT at 254 nm are qualitatively comparable (the cis-syn cyclobutane pyrimidine dimer and the (6-4) photoproduct are formed), although it is significantly faster in the case of 1a. These results are explained by the increased propensity of the modified dinucleotide to adopt a base-stacked conformation geometry reminiscent of that for TpT.