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Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate.
Chemistry 2007; 13(16):4571-81C

Abstract

Peroxynitrite is produced during inflammation and combines rapidly with carbon dioxide to yield the unstable nitrosoperoxycarbonate, which decomposes (in part) to CO(3) (.-) and (.)NO(2) radicals. The CO(3) (.-) radicals oxidize guanine bases in DNA through a one-electron transfer reaction process that ultimately results in the formation of stable guanine oxidation products. Here we have explored these mechanisms, starting with a spectroscopic study of the kinetics of electron transfer from 20-22mer double-stranded oligonucleotides to CO(3) (.-) radicals, together with the effects of base sequence on the formation of the end-products in runs of one, two, or three contiguous guanines. The distributions of these alkali-labile lesions were determined by gel electrophoresis methods. The cascade of events was initiated through the use of 308 nm XeCl excimer laser pulses to generate CO(3) (.-) radicals by an established method based on the photodissociation of persulfate to sulfate radicals and the oxidation of bicarbonate. Although the Saito model (Saito et al., J. Am. Chem. Soc. 1995, 117, 6406-6407) predicts relative ease of one-electron oxidations in DNA, following the trend 5'-GGG > 5'-GG > 5'-G, we found that the rate constants for CO(3) (.-)-mediated oxidation of guanines in these sequence contexts (k(5)) showed only small variation within a narrow range [(1.5-3.0)x10(7) M(-1) s(-1)]. In contrast, the distributions of the end-products are dependent on the base sequence context and are higher at the 5'-G in 5'-GG sequences and at the first two 5'-guanines in the 5'-GGG sequences. These effects are attributed to a combination of initial hole distributions among the contiguous guanines and the subsequent differences in chemical reaction yields at each guanine. The lack of dependence of k(5) on sequence context indicates that the one-electron oxidation of guanine in DNA by CO(3) (.-) radicals occurs by an inner-sphere mechanism.

Authors+Show Affiliations

Chemistry Department, New York University, 31 Washington Place, New York, NY 10003-5180, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17335089

Citation

Lee, Young Ae, et al. "Mechanisms of Oxidation of Guanine in DNA By Carbonate Radical Anion, a Decomposition Product of Nitrosoperoxycarbonate." Chemistry (Weinheim an Der Bergstrasse, Germany), vol. 13, no. 16, 2007, pp. 4571-81.
Lee YA, Yun BH, Kim SK, et al. Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate. Chemistry. 2007;13(16):4571-81.
Lee, Y. A., Yun, B. H., Kim, S. K., Margolin, Y., Dedon, P. C., Geacintov, N. E., & Shafirovich, V. (2007). Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate. Chemistry (Weinheim an Der Bergstrasse, Germany), 13(16), pp. 4571-81.
Lee YA, et al. Mechanisms of Oxidation of Guanine in DNA By Carbonate Radical Anion, a Decomposition Product of Nitrosoperoxycarbonate. Chemistry. 2007;13(16):4571-81. PubMed PMID: 17335089.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate. AU - Lee,Young Ae, AU - Yun,Byeong Hwa, AU - Kim,Seog K, AU - Margolin,Yelena, AU - Dedon,Peter C, AU - Geacintov,Nicholas E, AU - Shafirovich,Vladimir, PY - 2007/3/6/pubmed PY - 2007/8/31/medline PY - 2007/3/6/entrez SP - 4571 EP - 81 JF - Chemistry (Weinheim an der Bergstrasse, Germany) JO - Chemistry VL - 13 IS - 16 N2 - Peroxynitrite is produced during inflammation and combines rapidly with carbon dioxide to yield the unstable nitrosoperoxycarbonate, which decomposes (in part) to CO(3) (.-) and (.)NO(2) radicals. The CO(3) (.-) radicals oxidize guanine bases in DNA through a one-electron transfer reaction process that ultimately results in the formation of stable guanine oxidation products. Here we have explored these mechanisms, starting with a spectroscopic study of the kinetics of electron transfer from 20-22mer double-stranded oligonucleotides to CO(3) (.-) radicals, together with the effects of base sequence on the formation of the end-products in runs of one, two, or three contiguous guanines. The distributions of these alkali-labile lesions were determined by gel electrophoresis methods. The cascade of events was initiated through the use of 308 nm XeCl excimer laser pulses to generate CO(3) (.-) radicals by an established method based on the photodissociation of persulfate to sulfate radicals and the oxidation of bicarbonate. Although the Saito model (Saito et al., J. Am. Chem. Soc. 1995, 117, 6406-6407) predicts relative ease of one-electron oxidations in DNA, following the trend 5'-GGG > 5'-GG > 5'-G, we found that the rate constants for CO(3) (.-)-mediated oxidation of guanines in these sequence contexts (k(5)) showed only small variation within a narrow range [(1.5-3.0)x10(7) M(-1) s(-1)]. In contrast, the distributions of the end-products are dependent on the base sequence context and are higher at the 5'-G in 5'-GG sequences and at the first two 5'-guanines in the 5'-GGG sequences. These effects are attributed to a combination of initial hole distributions among the contiguous guanines and the subsequent differences in chemical reaction yields at each guanine. The lack of dependence of k(5) on sequence context indicates that the one-electron oxidation of guanine in DNA by CO(3) (.-) radicals occurs by an inner-sphere mechanism. SN - 0947-6539 UR - https://www.unboundmedicine.com/medline/citation/17335089/Mechanisms_of_oxidation_of_guanine_in_DNA_by_carbonate_radical_anion_a_decomposition_product_of_nitrosoperoxycarbonate_ L2 - https://doi.org/10.1002/chem.200601434 DB - PRIME DP - Unbound Medicine ER -