Populations and Dynamics of Guanine Radicals in DNA strands-Direct versus Indirect Generation.

ABSTRACT: Guanine radicals, known to be involved in the damage of the genetic code and aging, are studied by nanosecond transient absorption spectroscopy. They are generated in single, double and four-stranded structures (G-quadruplexes) by one and two-photon ionization at 266 nm, corresponding to a photon energy lower than the ionization potential of nucleobases. The quantum yield of the one-photon process determined for telomeric G-quadruplexes (TEL25/Na⁺) is (5.2 ± 0.3) × 10^-3, significantly higher than that found for duplexes containing in their structure GGG and GG sequences, (2.1 ± 0.4) × 10^-3. The radical population is quantified in respect of the ejected electrons. Deprotonation of radical cations gives rise to (G-H1)^• and (

SUBMITTER: Balanikas E 

PROVIDER: S-EPMC6651618 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature