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Direct observation of guanine radical cation deprotonation in duplex DNA using pulse radiolysis.
J Am Chem Soc. 2003 Aug 27; 125(34):10213-8.JA

Abstract

The dynamics of one-electron oxidation of guanine (G) base mononucleotide and that in DNA have been investigated by pulse radiolysis. The radical cation (G+*) of deoxyguanosine (dG), produced by oxidation with SO(4)-*, rapidly deprotonates to form the neutral G radical (G(-H)*) with a rate constant of 1.8 x 10(7) s(-1) at pH 7.0, as judged from transient spectroscopy. With experiments using different double-stranded oligonucleotides containing G, GG, and GGG sequences, the absorbance increases at 625 nm, characteristic of formation of the G(-H)*, were found to consist of two phases. The rate constants of the faster (approximately 1.3 x 10(7) s(-1)) and slower phases (approximately 3.0 x 10(6) s(-1)) were similar for the different oligonucleotides. On the other hand, in the oligonucleotide containing G located at the 5'- and 3'-terminal positions, only the faster phase was seen. These results suggest that the lifetime of the radical cation of the G:C base pair (GC+*), depending on its location in the DNA chain, is longer than that of free dG. In addition, the absorption spectral intermediates showed that hole transport to a specific G site within a 12-13mer double-stranded oligonucleotide is complete within 50 ns; that is, the rate of hole transport over 20 A is >10(7) s(-1).

Authors+Show Affiliations

The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki Osaka 567-0047, Japan. kobayashi@sanken-osaka.u.ac.jpNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12926943

Citation

Kobayashi, Kazuo, and Seiichi Tagawa. "Direct Observation of Guanine Radical Cation Deprotonation in Duplex DNA Using Pulse Radiolysis." Journal of the American Chemical Society, vol. 125, no. 34, 2003, pp. 10213-8.
Kobayashi K, Tagawa S. Direct observation of guanine radical cation deprotonation in duplex DNA using pulse radiolysis. J Am Chem Soc. 2003;125(34):10213-8.
Kobayashi, K., & Tagawa, S. (2003). Direct observation of guanine radical cation deprotonation in duplex DNA using pulse radiolysis. Journal of the American Chemical Society, 125(34), 10213-8.
Kobayashi K, Tagawa S. Direct Observation of Guanine Radical Cation Deprotonation in Duplex DNA Using Pulse Radiolysis. J Am Chem Soc. 2003 Aug 27;125(34):10213-8. PubMed PMID: 12926943.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Direct observation of guanine radical cation deprotonation in duplex DNA using pulse radiolysis. AU - Kobayashi,Kazuo, AU - Tagawa,Seiichi, PY - 2003/8/21/pubmed PY - 2004/1/14/medline PY - 2003/8/21/entrez SP - 10213 EP - 8 JF - Journal of the American Chemical Society JO - J. Am. Chem. Soc. VL - 125 IS - 34 N2 - The dynamics of one-electron oxidation of guanine (G) base mononucleotide and that in DNA have been investigated by pulse radiolysis. The radical cation (G+*) of deoxyguanosine (dG), produced by oxidation with SO(4)-*, rapidly deprotonates to form the neutral G radical (G(-H)*) with a rate constant of 1.8 x 10(7) s(-1) at pH 7.0, as judged from transient spectroscopy. With experiments using different double-stranded oligonucleotides containing G, GG, and GGG sequences, the absorbance increases at 625 nm, characteristic of formation of the G(-H)*, were found to consist of two phases. The rate constants of the faster (approximately 1.3 x 10(7) s(-1)) and slower phases (approximately 3.0 x 10(6) s(-1)) were similar for the different oligonucleotides. On the other hand, in the oligonucleotide containing G located at the 5'- and 3'-terminal positions, only the faster phase was seen. These results suggest that the lifetime of the radical cation of the G:C base pair (GC+*), depending on its location in the DNA chain, is longer than that of free dG. In addition, the absorption spectral intermediates showed that hole transport to a specific G site within a 12-13mer double-stranded oligonucleotide is complete within 50 ns; that is, the rate of hole transport over 20 A is >10(7) s(-1). SN - 0002-7863 UR - https://www.unboundmedicine.com/medline/citation/12926943/Direct_observation_of_guanine_radical_cation_deprotonation_in_duplex_DNA_using_pulse_radiolysis_ L2 - https://dx.doi.org/10.1021/ja036211w DB - PRIME DP - Unbound Medicine ER -