Cited by 26DNA and Nucleic Acid ChemistryDNA Repair MechanismsCarcinogens and Genotoxicity Assessment

A New Photoproduct of 5-Methylcytosine and Adenine Characterized by High-Performance Liquid Chromatography and Mass Spectrometry

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Su, Dian G. T., Taylor, John-Stephen A., Gross, Michael L.·2010·Chemical Research in Toxicology

Abstract

The UV portion of sunlight is mutagenic and can modify DNA by producing various photoproducts. UV photodamage often occurs at dipyrimidine sites, to give cyclobutane, pyrimidine-(6-4)-pyrimidone (6-4), and pyrimidine-(6-4)-Dewar pyrimidone (Dewar) photoproducts, and at TA and AA sites. There is no reported evidence, however, of UV photoproduct formation between C or 5-methylC ((m)C) and A. Irradiation of d(GTAT(m)CATGAGGTGC) with UVB light at physiological pH gives an unexpected photoproduct that undergoes fast thermal deamination but does not revert to its original structure under UVC irradiation. Evidence from nuclease P1 digestion coupled with electrospray ionization (ESI)-MS/MS is in accord with product formation between (m)C and A. HPLC analysis indicates that deamination gives a T<>A photoproduct that coelutes on reverse-phase chromatography with the well-known TA* photoproduct, formed from an initial [2 + 2] reaction between C5-C6 and C6-C5 of the adjacent thymine and adenine [as shown by Zhao , X. , et al. ( 1996 ) Nucleic Acids Res. 24 , 1554 - 1560 and Davies , R. J. , et al. ( 2007 ) Nucleic Acids Res. 35 , 1048 - 1053 ]. Furthermore, the deamination product of the unknown (m)C<>A photoproduct and the TA* photoproduct undergo nearly identical fragmentation in tandem MS. The evidence, taken together, indicates that the deamination product of the unknown (m)CA photoproduct has the same chemical structure as the TA* photoproduct. Therefore, the unknown photoproduct is referred to as the (m)CA* photoproduct, which, upon deamination, gives the TA* photoproduct.

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  • Su et al. reported a new photoproduct of 5-methylcytosine and adenine characterized by HPLC and mass spectrometry.

    “However, Su et al. [61] have reported a new photoproduct of 5-Methylcytosine and Adenine characterized by high-performance liquid chromatography and mass spectrometry.”

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Authors
Su, D. G. T., Taylor, J.-S. A., & Gross, M. L.
Affiliations
Washington University in St. Louis (US)
Corresponding author
  • Taylor, John-Stephen A.
  • Gross, Michael L.
Venue
Chemical Research in Toxicology
Published
2010-02-17
Volume
23
Issue
3
Pages
474-479
ISSN
  • 0893-228X (ISSN-L)
  • 1520-5010
OpenAlex
W2026752855
Cited by
26
References
42
Citations by year
2026: 1 · 2025: 1 · 2023: 1 · 2021: 1 · 2020: 3 · 2018: 1 · 2015: 1 · 2014: 4 · 2013: 4 · 2012: 1
FWCI
1.69
Type
journal article
Language
en
Open access
Locations
  • Chemical Research in Toxicology (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Institutes of Health (5p41rr000954-34)
  • National Cancer Institute (R01CA040463, R37CA040463, CA40463)
  • National Institute of General Medical Sciences (P41GM103422)
  • National Center for Research Resources (P41-RR000954)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › DNA and Nucleic Acid Chemistry
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › DNA Repair Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Carcinogens and Genotoxicity Assessment
Keywords
5-methylcytosine, adenine, UV photoproducts, UVB irradiation, [2+2] cycloaddition, DNA photodamage, tandem mass spectrometry, electrospray ionization
MeSH terms
Adenine, Base Sequence, Chromatography, High Pressure Liquid, DNA, Photochemistry, Mass Spectrometry, Ultraviolet Rays, 5-Methylcytosine

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