Electron transfer between guanosine radicals and amino acids in aqueous solution. II. Reduction of guanosine radicals by tryptophan

Electron transfer between guanosine radicals and amino acids in aqueous solution. II. Reduction of guanosine radicals by tryptophan Full article

Journal

The Journal of Physical Chemistry B
ISSN: 1520-6106

Output data

Year: 2008, Volume: 112, Number: 9, Pages: 2747-2754 Pages count : 8 DOI: 10.1021/Jp0752318

Tags

time-resolved cidnp, laser flash-photolysis, oxidative DNA-damage, hyperfine coupling-constants, guanyl radicals, proton-transfer, tyrosine, peptide, plasmid DNA, repair, 2,2'-dipyridyl

Authors

Morozova Olga B. ¹ , Kiryutin Alexey S. ^1,2 , Yurkovskaya Alexandra V. ^1,3

Affiliations

1	International Tomography Center of SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia,
2	Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia,
3	Institute of Experimental Physics, Free University of Berlin, Arnimallee 14, 14195 Berlin, Germany

The efficiency of the chemical pathway of DNA repair is studied by time-resolved chemically induced dynamic nuclear polarization (CIDNP) using the model system containing guanosyl base radicals, and tryptophan as the electron donor. Radicals were generated photochemically by pulsed laser irradiation of a solution containing the photosensitizer 2,2'-dipyridyl, guanosine-5'-monophosphate, and N-acetyl tryptophan. Depending on the pH of the aqueous solution, four protonation states of the guanosyl radical are formed via electron or hydrogen atom transfer to the triplet excited dye. The rate constants of electron transfer from the amino acid to the guanosyl radical were determined by quantitative analysis of the CIDNP kinetics, which is very sensitive to the efficiency of radical reactions in the bulk, and rate constants vary from (1.0 +/- 0.3) x 10(9) M-1 s(-1) for the cation and dication radicals of the nucleotide to (1.2 +/- 0.3) x 10(7) M-1 s(-1) for the radical in its anionic form. They were found to be higher than the corresponding values for electron transfer in the case of N-acetyl tyrosine as the reducing agent.

Morozova O.B. , Kiryutin A.S. , Yurkovskaya A.V.
Electron transfer between guanosine radicals and amino acids in aqueous solution. II. Reduction of guanosine radicals by tryptophan
The Journal of Physical Chemistry B. 2008. V.112. N9. P.2747-2754. DOI: 10.1021/Jp0752318 WOS OpenAlex

Submitted:	Jul 5, 2007
Published online:	Feb 12, 2008
Published print:	Mar 1, 2008

Web of science:	WOS:000253511900027
OpenAlex:	W2052637744

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