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Guanine of the third strand of C.G*G triplex serves as an effective hole trap.
J Am Chem Soc 2002; 124(49):14580-5JA

Abstract

We have examined the structural and electronic effects of the one-electron oxidation of the C.GG triplex, where G is located in a quite different environment from the G of duplex DNA. Upon photoirradiation of an external photosensitizer (riboflavin) with the C.GG triplex, oxidative DNA cleavage occurred exclusively at guanine repeat sequences in the third strand of triple helix DNA. Hole transport through the C.GG triplex also occurred, resulting in selective cleavage at G in the third strand. Thus, the hole generated in the duplex can migrate to GGG in the third strand and is trapped exclusively at Gs in the third strand. These experimental results, together with molecular orbital calculations, suggest that the origin of the selective strand cleavage can be explained as follows: (i) guanine repeat sequences in the third strand are more easily oxidized than in duplex DNA and (ii) in their radical cation states, G of the third strand rapidly deprotonates and reacts with oxygen and/or water, leading to strand cleavage. These results indicate that the oxidative damage preferentially occurred at Gs of the third strand owing to thermodynamic and kinetic features of the one-electron oxidation of the C.GG triplex.

Authors+Show Affiliations

Department of Synthetic Chemistry and Biological Chemistry, Faculty of Engineering, Kyoto University, CREST, Japan Science and Technology Corporation (JST), Kyoto 606-8501, Japan.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12465967

Citation

Dohno, Chikara, et al. "Guanine of the Third Strand of C.G*G Triplex Serves as an Effective Hole Trap." Journal of the American Chemical Society, vol. 124, no. 49, 2002, pp. 14580-5.
Dohno C, Nakatani K, Saito I. Guanine of the third strand of C.G*G triplex serves as an effective hole trap. J Am Chem Soc. 2002;124(49):14580-5.
Dohno, C., Nakatani, K., & Saito, I. (2002). Guanine of the third strand of C.G*G triplex serves as an effective hole trap. Journal of the American Chemical Society, 124(49), pp. 14580-5.
Dohno C, Nakatani K, Saito I. Guanine of the Third Strand of C.G*G Triplex Serves as an Effective Hole Trap. J Am Chem Soc. 2002 Dec 11;124(49):14580-5. PubMed PMID: 12465967.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Guanine of the third strand of C.G*G triplex serves as an effective hole trap. AU - Dohno,Chikara, AU - Nakatani,Kazuhiko, AU - Saito,Isao, PY - 2002/12/6/pubmed PY - 2003/2/13/medline PY - 2002/12/6/entrez SP - 14580 EP - 5 JF - Journal of the American Chemical Society JO - J. Am. Chem. Soc. VL - 124 IS - 49 N2 - We have examined the structural and electronic effects of the one-electron oxidation of the C.GG triplex, where G is located in a quite different environment from the G of duplex DNA. Upon photoirradiation of an external photosensitizer (riboflavin) with the C.GG triplex, oxidative DNA cleavage occurred exclusively at guanine repeat sequences in the third strand of triple helix DNA. Hole transport through the C.GG triplex also occurred, resulting in selective cleavage at G in the third strand. Thus, the hole generated in the duplex can migrate to GGG in the third strand and is trapped exclusively at Gs in the third strand. These experimental results, together with molecular orbital calculations, suggest that the origin of the selective strand cleavage can be explained as follows: (i) guanine repeat sequences in the third strand are more easily oxidized than in duplex DNA and (ii) in their radical cation states, G of the third strand rapidly deprotonates and reacts with oxygen and/or water, leading to strand cleavage. These results indicate that the oxidative damage preferentially occurred at Gs of the third strand owing to thermodynamic and kinetic features of the one-electron oxidation of the C.GG triplex. SN - 0002-7863 UR - https://www.unboundmedicine.com/medline/citation/12465967/Guanine_of_the_third_strand_of_C_G_G_triplex_serves_as_an_effective_hole_trap_ L2 - https://dx.doi.org/10.1021/ja026724n DB - PRIME DP - Unbound Medicine ER -