Journal of Physical Chemistry B, Vol.112, No.33, 10375-10381, 2008
Chemical stability and reactivity of deprotonated oligonucleotides (DNA) in the gas phase: Protonation and solvation with hydrogen bromide
Selected deprotonated oligodeoxynucleotides generated by electrospray ionization were exposed to a variety of neutral molecules in the gas phase at room temperature in flowing helium gas at 0.35 Torr. Single-stranded [AGTCTG-nH]"- and single- and double-stranded [GCATGC-nH]n- anions were found to be remarkably unreactive with strong oxidants (03, 02, N20) and potential intercalators (benzene, pyridine, toluene, and quinoxaline). Hydration also was observed to be inefficient. However, [AGTCTG-nHIn- anions with n = 2, 3, 4, and 5 were seen to be sequentially protonated and/or hydrobrominated with H13r (but not damaged) and displayed an interesting "end effect" against protonation. Measurements are provided for the rate coefficients of reaction and the efficiencies of protonation. These experimental results point toward the exciting prospect of measuring the intrinsic chemistry of other bare DNA-like anions, including double-stranded oligonucleotide anions in the gas phase at room temperature.