Products of riboflavin-mediated photosensitization of 2′-deoxyguanosine (dG) and thymidylyl-(3′-5′)-2′-deoxyguanosine (TpdG) by 350-nm light in oxygen-saturated aqueous solution have been isolated and identified as 1-(2-deoxy-β-d-erythro-pentofuranosyl) oxaluric acid (β-dOx) and thymidylyl-(3′-5′)-1-(2-deoxy-β-d-erythro-pentofuranosyl) oxaluric acid (Tpβ-dOx), respectively. In aqueous solution the modified β-deoxyribonucleoside is slowly converted to the α-anomer, generating α-dOx and Tpα-dOx. These modified nucleosides and dinucleoside monophosphates have been isolated by HPLC and characterized by proton and carbon NMR spectroscopy, fast atom bombardment mass spectrometry, and enzymatic analyses. Both α-dOx and Tpα-dOx slowly convert back into the modified β-deoxyribonucleoside, indicating that the furanosidic anomers are in dynamic equilibrium. Relative to TpdG, the rate of hydrolysis of Tpβ-dOx and Tpα-dOx by spleen phosphodiesterase is greatly reduced. Hot piperidine (1.0 M, 90°C, 30 min) destroys Tpβ-dOx and Tpα-dOx. Riboflavin-mediated photosensitization of TpdG in D2O instead of H2O has no detectable effect on the yield of Tpβ-dOx, suggesting that oxaluric acid is generated through a Type-I reaction mechanism, likely through the intermediary on initially generated 8-oxo-7,8-dihydro-2′-deoxyguanosine.
How to translate text using browser tools
1 January 2006
Identification of the α and β Anomers of 1-(2-Deoxy-d-Erythro-Pentofuranosyl)-Oxaluric Acid at the Site of Riboflavin-mediated Photooxidation of Guanine in 2′-Deoxyguanosine and Thymidylyl-(3′-5′)-2′-Deoxyguanosine
Garry W. Buchko,
Jean Cadet
ACCESS THE FULL ARTICLE
It is not available for individual sale.
This article is only available to subscribers.
It is not available for individual sale.
It is not available for individual sale.
Photochemistry and Photobiology
Vol. 82 • No. 1
January 2006
Vol. 82 • No. 1
January 2006