Skip to main content
PMC home page
Nucleic Acids Research logoLink to Nucleic Acids Research
. 1984 Oct 25;12(20):7929–7947. doi: 10.1093/nar/12.20.7929

The photochemistry of d(T-A) in aqueous solution and in ice.

S N Bose, S Kumar, R J Davies, S K Sethi, J A McCloskey
PMCID: PMC320218  PMID: 6493984

Abstract

When d(T-A) is irradiated at 254 nm in aqueous solution an internal photoadduct is formed between its constituent adenine and thymine bases. The resultant photoproduct, designated TA*, arises from a singlet excited state precursor; a similar photoreaction is not observed with d(C-A) or d(T-G). In contradistinction, irradiation of d(T-A) in frozen aqueous solution yields a dimeric photoproduct in which two d(T-A) molecules are coupled together by a (6-4) photoadduct linkage between their respective thymine bases. Both photoproducts have been extensively characterised by a combination of electron impact and fast atom bombardment mass spectrometry, UV, CD, 1H NMR and fluorescence spectroscopy. Acid treatment of TA* gives 6-methylimidazo[4,5-b]pyridin-5-one whose identity was established by an independent chemical synthesis involving photorearrangement of 6-methyl-imidazo[4,5-b]pyridine N(4)-oxide. A tentative mechanism is presented to account for the acid degradation of TA*. The structure of the dimeric ice photoproduct follows from its cleavage, by snake venom phosphodiesterase, to 5'-dAMP and the (6-4) bimolecular photoadduct of thymidine; on acid hydrolysis it gives adenine and 6-(5'-methyl-2'-oxopyrimidin-4'-yl) thymine.

Full text

PDF
7929

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bose S. N., Davies R. J., Sethi S. K., McCloskey J. A. Formation of an adenine-thymine photoadduct in the deoxydinucleoside monophosphate d(TpA) and in DNA. Science. 1983 May 13;220(4598):723–725. doi: 10.1126/science.6836308. [DOI] [PubMed] [Google Scholar]
  2. Bose S. N., Davies R. J. The photoreactivity of T-A sequences in oligodeoxyribonucleotides and DNA. Nucleic Acids Res. 1984 Oct 25;12(20):7903–7914. doi: 10.1093/nar/12.20.7903. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cheng D. M., Sarma R. H. Intimate details of the conformational characteristics of deoxyribodinucleoside monophosphates in aqueous solution. J Am Chem Soc. 1977 Oct 26;99(22):7333–7348. doi: 10.1021/ja00464a038. [DOI] [PubMed] [Google Scholar]
  4. Franklin W. A., Lo K. M., Haseltine W. A. Alkaline lability of fluorescent photoproducts produced in ultraviolet light-irradiated DNA. J Biol Chem. 1982 Nov 25;257(22):13535–13543. [PubMed] [Google Scholar]
  5. Horne D. S., Parker T. G. Polynomial representation of digital spectrophotometric data of amino acids and proteins. Biochim Biophys Acta. 1980 Sep 23;625(1):18–27. doi: 10.1016/0005-2795(80)90104-x. [DOI] [PubMed] [Google Scholar]
  6. Karle I. L. Crystal structure of a thymine-thymine adduct from irradiated thymine. Acta Crystallogr B. 1969 Oct 15;25(10):2119–2126. doi: 10.1107/s056774086900522x. [DOI] [PubMed] [Google Scholar]
  7. Lawson A. M., Stillwell R. N., Tacker M. M., Tsuboyama K., McCloskey J. A. Mass spectrometry of nucleic acid components. Trimethylsilyl derivatives of nucleotides. J Am Chem Soc. 1971 Feb 24;93(4):1014–1023. doi: 10.1021/ja00733a039. [DOI] [PubMed] [Google Scholar]
  8. Rahn R. O. Search for an adenine photoproduct in DNA. Nucleic Acids Res. 1976 Apr;3(4):879–890. doi: 10.1093/nar/3.4.879. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Varghese A. J. Photochemistry of thymidine in ice. Biochemistry. 1970 Nov 24;9(24):4781–4787. doi: 10.1021/bi00826a023. [DOI] [PubMed] [Google Scholar]
  10. Varghese A. J., Wang S. Y. Thymine-thymine adduct as a photoproduct of thymine. Science. 1968 Apr 12;160(3824):186–187. doi: 10.1126/science.160.3824.186. [DOI] [PubMed] [Google Scholar]

Articles from Nucleic Acids Research are provided here courtesy of Oxford University Press

RESOURCES