Ultrafast excited state deactivation and energy transfer in guanine-cytosine DNA double helices

F.A. Miannay (1) , A. Bányász (1) , T. Gustavsson (1) , D. Markovitsi (1)

1 LFP - URA 2453 - Laboratoire Francis PERRIN

The stability of DNA components with respect to UV radiation is considered to be a prerequisite for the development of the genetic code. But it is also known that UV light absorbed by DNA bases may damage the double helix and lead to carcinogenic mutations.1 The interplay between stability and photodamage depends on the way that the energy of a UV photon is distributed among the electronic excited states of the double helix before it is eliminated as heat. Ultrafast dissipation of the excitation energy is indeed a common property of all the monomeric DNA building blocks: the major part of the excited state population of nucleosides and nucleotides in aqueous solution lives for less than one picosecond.2,3 When applied to double helices, composed exclusively of adenine-thymine base pairs (A-T duplexes, both homopolymeric and alternating), femtosecond spectroscopy reveals a different picture: organization of the bases within duplexes causes an overall lengthening of the excited state lifetimes.4-9 This is due to the emergence of new excited states, shared between at least two bases. The existence of delocalized excited states allows ultrafast energy transfer to occur5,8-10 by-passing the prerequisites of Förster transfer which are not fulfilled in the case of DNA bases.

Domaines: Chimie théorique et/ou physique

F.A. Miannay, A. Bányász, T. Gustavsson, D. Markovitsi. Ultrafast excited state deactivation and energy transfer in guanine-cytosine DNA double helices. Journal of the American Chemical Society, 2007, 129, pp.14574-14575. ⟨10.1021/ja077100q⟩. ⟨hal-00192704⟩