Oligonucleotide covalent modifications by estrogen quinones evidenced by use of liquid chromatography coupled to negative electrospray ionization tandem mass spectrometry

Liquid chromatography coupled to tandem mass spectrometry has been used for the detection and the structural characterization of T-rich model oligonucleotides covalently modified by estradiol-2,3-quinone. After separation by gradient elution, adducts were analyzed by negative electrospray mass spectrometry, enabling to evidence and localize the modifications in the oligonucleotide sequence. Modifications by one molecule of estrogen were evidenced on purines (A, G) whereas no reaction was observed on pyrimidic bases (T). Isomeric adducts were differentiated using tandem mass spectrometry, and energy resolved mass spectrometry allowed to underline differences in the behavior of the adducts towards collisional excitation into an ion trap device.