Science article hot of the press (published 10 October 2008)
10 October 2008:
Base Sequence and Higher-Order Structure Induce the Complex Excited-State Dynamics in DNA
Nina K. Schwalb and Friedrich Temps
Science 322, 243 - 245 (2008), DOI: 10.1126/science.1161651
DNA dissipates ultraviolet light more effectively when it consists of a mixed sequence than when it is an extended run of the same nucleotide.
The high photostability of DNA is commonly attributed to efficient radiationless electronic relaxation processes. We used femtosecond time-resolved fluorescence spectroscopy to reveal that the ensuing dynamics are strongly dependent on base sequence and are also affected by higher-order structure. Excited electronic state lifetimes in dG-doped d(A)20single-stranded DNA and dG·dC-doped d(A)20·d(T)20 double-stranded DNA decrease sharply with the substitution of only a few bases. In duplexes containing d(AGA)·d(TCT) or d(AG)·d(TC) repeats, deactivation of the fluorescing states occurs on the subpicosecond time scale, but the excited-state lifetimes increase again in extended d(G) runs. The results point at more complex and molecule-specific photodynamics in native DNA than may be evident in simpler model systems.Abstract in Science Download as HTML Download as PDF Supporting Online Information