TRIPLET EXCITED STATES OF 4',5'-PHOTOMONOADDUCTS OF 3- CARBETHOXYPSORALEN and 8-METHOXYPSORALEN WITH DNA NUCLEOSIDES |
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| Authors: | J Blais J C Ronfard-Haret P Vigny J Cadet L Voituriez |
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| Institution: | Laboratoire de Physique et Chimie Biomoleculaire (LA CNRS 198), Institut Curie, Section de Physique et Chimie, 11, rue Pierre et Marie Curie, 75231 Paris C6dex 05, France;Laboratoire de Biophysique. INSERM U 201. CNRS ERA 951 Muséum National d'Histoire Naturelle, 62, rue Buffon. 75231 Paris Cédex 05, France;Laboratoires de Chimie, Département de Recherche Fondamentale, Centre d'Etudes Nucleaires de Grenoble, 85-X 38041 Grenoble, France |
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| Abstract: | Abstract— Triplet absorption spectra, triplet extinction coefficient and intersystem crossing for 4',5'-monocycloadducts of 3-carbethoxypsoralen (3-CPs) with thymidine (dThd) and uridine (dUrd) in ethanol have been investigated in order to elucidate whether their triplet state properties could be the limitating step for a further photoreaction of 3-CPs monoadducts with DNA nucleosides. The comparison between the triplet characteristics of 4',5'-monoadducts of 3-CPs and those of 8-methoxypsoralen (8-MOP) shows that the quantum yield is much higher in the case of 3-CPs than for 8-MOP. The monofunctionality of 3-CPs cannot therefore be ascribed to the triplet excited states properties of its monoadducts. It is likely that steric hindrance introduced by the bulky carbethoxy group remains a reasonable explanation. |
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