Isolation and mass spectrometric characterization of dimeric adenine photoproducts in oligodeoxynucleotides.
UVC irradiation of oligodeoxynucleotides (ODNs) at 254 nm generates two types of DNA photoproducts, A=A and (AA)*, at adjacent adenine sites in DNA. Kumar et al. previously proved the structure of these adducts in dinucleoside monophosphates [Kumar, S., et al. (1987) Nucleic Acids Res. 15, 1199-1216; Kumar, S., et al. (1991) Nucleic Acids Res. 19, 2841-2847]. Product-ion spectra of ESI-produced [M - 2H](2-) ions of the ODNs containing the dimeric adenine photoproducts show distinctive fragmentation that is informative of the structures of the photoproducts. The gas-phase cleavages of ODNs at sites of those photoproducts and thymine thymine or thymine adenine ((TA)*) photoproducts are analogous to cleavages induced by hot alkaline treatment. Nuclease-P1 digestions of ODNs containing dimeric adenine photoproducts give shorter pieces of ODNs bearing the photoproducts, which fragment under collisional activation conditions in a similar way to the large ODNs containing the photoproducts. The tandem mass spectrometric results show that the yield of (AA)* is lower than that of A=A when adjacent adenines are in the middle of an ODN sequence, and the yield of the latter is similar to that of (TA)*.
Wang
Y
Y
Department of Chemistry, Washington University, One Brookings Drive, St. Louis, Missouri 63130, USA.
Taylor
J S
JS
Gross
M L
ML
D000225:Adenine / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D018736:DNA Adducts / Q000737:chemistry* / Q000302:isolation & purification; D019281:Dimerization; D006801:Humans; D013058:Mass Spectrometry; D009841:Oligonucleotides / Q000737:chemistry*; D010777:Photochemistry; D014466:Ultraviolet Rays
D018736:DNA Adducts; D009841:Oligonucleotides; D000225:Adenine