Tandem mass spectrometry is evaluated to study the stability of higher-order structures of biomolecules in the gas-phase. Upon collisional activation, DNA:DNA duplexes dissociate via strand separation. For highly modified nucleic acids, by contrast, the ejection of backbone fragments from the duplex presents an alternative fragmentation channel accessible at similar activation energies.
This observation contests the fundamental hypothesis that non-covalent interactions are overcome before the cleavage of covalent bonds and highlights the contribution of the activation entropy to reactions in the gas-phase.

This work was carried out in the group of PD Dr. Stefan Schürch.

References:

• Y. Hari, B. Dugovic, A. Istrate, A. Fignolé, C. J. Leumann, S. Schürch;
  "The Contribution of the Activation Entropy to the Gas-Phase Stability of Modified Nucleic Acid Duplexes"
  J. Am. Soc. Mass Spectrom., 2016, 27(7), 1186-1196; doi:10.1007/s13361-016-1391-3.