Research output: Contribution to journal › Article › peer-review
Kinetics of Reversible Protonation of Transient Neutral Guanine Radical in Neutral Aqueous Solution. / Morozova, Olga B.; Fishman, Natalya N.; Yurkovskaya, Alexandra V.
In: ChemPhysChem, Vol. 19, No. 20, 19.10.2018, p. 2696-2702.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Kinetics of Reversible Protonation of Transient Neutral Guanine Radical in Neutral Aqueous Solution
AU - Morozova, Olga B.
AU - Fishman, Natalya N.
AU - Yurkovskaya, Alexandra V.
N1 - Publisher Copyright: © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/10/19
Y1 - 2018/10/19
N2 - Time-resolved chemically induced dynamic nuclear polarization (TR-CIDNP) is applied to follow transformation of the short-lived neutral guanine radical into a secondary guanine radical by its protonation, presumably at position N7. In the initial step the photoreaction of guanosine-5′-monophosphate (GMP) with triplet excited 3,3′,4,4′-tetracarboxy benzophenone (TCBP) leads to formation of the neutral radical G(−H).. The evidence of the radical conversion is based on the inversion of CIDNP sign for TCBP and GMP protons on the microsecond timescale as a result of the change in magnetic resonance parameters in the pairs of TCBP and GMP radicals due to structural changes of the GMP radical. Acceleration of the CIDNP sign change upon addition of phosphate (proton donor) confirms that the radical transformation responsible for the observed CIDNP kinetics is protonation of the neutral guanine radical with formation of the newly characterized cation radical, (G.+)′. From the full analysis of the pH-dependent CIDNP kinetics, the protonation and deprotonation behaviour is quantitatively characterized, giving pKa=8.0±0.2 of the cation radical (G.+)′.
AB - Time-resolved chemically induced dynamic nuclear polarization (TR-CIDNP) is applied to follow transformation of the short-lived neutral guanine radical into a secondary guanine radical by its protonation, presumably at position N7. In the initial step the photoreaction of guanosine-5′-monophosphate (GMP) with triplet excited 3,3′,4,4′-tetracarboxy benzophenone (TCBP) leads to formation of the neutral radical G(−H).. The evidence of the radical conversion is based on the inversion of CIDNP sign for TCBP and GMP protons on the microsecond timescale as a result of the change in magnetic resonance parameters in the pairs of TCBP and GMP radicals due to structural changes of the GMP radical. Acceleration of the CIDNP sign change upon addition of phosphate (proton donor) confirms that the radical transformation responsible for the observed CIDNP kinetics is protonation of the neutral guanine radical with formation of the newly characterized cation radical, (G.+)′. From the full analysis of the pH-dependent CIDNP kinetics, the protonation and deprotonation behaviour is quantitatively characterized, giving pKa=8.0±0.2 of the cation radical (G.+)′.
KW - DNA oxidation
KW - guanine radical
KW - NMR spectroscopy
KW - photo-oxidation
KW - photochemistry
UR - http://www.scopus.com/inward/record.url?scp=85055154096&partnerID=8YFLogxK
U2 - 10.1002/cphc.201800539
DO - 10.1002/cphc.201800539
M3 - Article
C2 - 29978943
AN - SCOPUS:85055154096
VL - 19
SP - 2696
EP - 2702
JO - ChemPhysChem
JF - ChemPhysChem
SN - 1439-4235
IS - 20
ER -
ID: 17247146