CEEPC/IPM/CMSC - Abstrakt prezentace

(CEEPC/IPM/CMSC 2022 - ThP-09)
Tandem Mass Spectrometry of DNA Codons: From Cations to Cation Radicals

Jiahao Wan 1, Yue Liu 1, Břetislav Brož 2, Aleš Marek 2 *, František Tureček 1

  1. University of Washington, Seattle, WA


Hydrogen-adducted radicals are important highly reactive intermediates formed by fast solvation following secondary electron capture in DNA. Unlike in the condensed phase, cation radicals generated in the gas phase by reductive electron transfer allow convenient isolation and characterization using tandem mass spectrometry. By studying the fragmentation patterns of cations and cation radicals for 64 DNA codons in the gas phase, we were able to create complete a map useful for the interpretation of oligonucleotide fragmentations. Nucleobase eliminations, as well as backbone cleavages were determined for different sequences in cations and cation radicals with the help of selectively N-15 labeled codons.

CID-MS2 spectra of monocations and dications showed neutral and protonated nucleobase eliminations following the trend: cytosine > guanine > adenine >> thymine and 5’ > 3’ > middle position. The most abundant backbone cleavage was forming w2 ions. Formation of d2 ions was not observed. To generate cation radicals while avoiding contamination by hydrogen-loss product isotope peaks, dication complexes of dibenzo crown ether and trinucleotides were formed and isolated for ETD-MS2. In ETD-CID-MS3 of cation radicals, nucleobase eliminations followed the same trend as with cations, involving both neutral bases and hydrogen-adducted base radicals. Surprisingly, abundant d2 fragments as well as w2 fragments were observed from cation radicals. The formation of w2, w2+H and w2+2H indicated that the radical was located on either the w2 or complementary a type moieties. In contrast, only even-electron d2 and d2+2H ions were produced in high abundance, indicating that the radicals were located on the complementary z fragments.

* Korespondující autor: ales.marek@uochb.cas.cz


  1. J. Wan, B. Brož, Y. Liu, S. R. Huang, A. Marek, F. Tureček; J. Am. Soc. Mass Spectrom. 2022, accepted.
  2. B. Brož, F. Tureček, A. Marek; J. Labelled Compd. Radiopharm. 2022, accepted.


This work was supported by the project INTER-EXCELLENCE LTAUSA19094 provided by the Ministry of Education, Youth and Sports of the Czech Republic, and an institutional support from the Czech Academy of Sciences (RVO: 61388963). Research at University of Washington was supported by the Chemistry Division of the U.S. National Science Foundation (Grant CHE-1951518).

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