Structural characterization of intact covalently linked DNA abducts by electrospray mass spectrometry

Electrospray mass spectrometry has aided the structural characterization of new series of intact covalently linked [DNA-(aromatic compounds)] adducts. The following DNA adducts with modified d-guanosine units were synthesized : d[CGTAC(GBA)], d[(CCACGTTAACGTGG)-(AAF)(n=1-4)] and d[(GATTCGTAGCTACGAATC )-(AAF)(n=1-4)] and were analyzed by negative electrospray mass spectrometr y. These DNA adducts exhibited different series of multiply charged deproto nated molecular anions. The mass spectra so obtained were of the whole mole cules, each having a number of negative charges, mostly in the range of -5 to -9. Fragmentations of the multiply charged deprotonated molecular anions formed by the [mer-14(GAAF)(n=1-4)] were obtained by controlled collisiona lly activated dissociation (CAD) initiated by cone voltage fragmentation an d afforded diagnostic product anions which confirmed the presence and locat ion of the guanine nucleobase adduct [Gua-C-8-AAF] and allowed bi-direction al sequencing of these DNA-carcinogen adducts. Low-energy collision activat ed dissocation of the precursor multiply charged anion F8- at m/z 796.72, p roduced from the [mer-18(GAAF)(4)+Na-H] adduct using a high collision energ y, provided some characteristic fingerprint product anions.