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Fast gas‐phase hydrogen/deuterium exchange observed for a DNA G‐quadruplex
Author(s) -
Gabelica Valérie,
Rosu Frederic,
Witt Matthias,
Baykut Gökhan,
De Pauw Edwin
Publication year - 2004
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1772
Subject(s) - chemistry , hydrogen–deuterium exchange , fourier transform ion cyclotron resonance , deuterium , mass spectrometry , ion , dissociation (chemistry) , ion cyclotron resonance , hydrogen , gas phase , ion exchange , crystallography , analytical chemistry (journal) , chromatography , cyclotron , organic chemistry , atomic physics , physics
The gas‐phase hydrogen/deuterium (H/D) exchange kinetics of DNA G‐quadruplexes has been investigated using Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). The quadruplex [(TGGGGT) 4 · 3NH 4 + ] undergoes very fast H/D exchange, in both the positive and in the negative ion modes, compared to DNA duplexes and other quadruplexes tested, and compared to the corresponding single‐stranded TGGGGT. Substitution of NH 4 +for K + did not alter this fast H/D exchange, indicating that the hydrogens of the ammonium ions are not those exchanged. However, stripping of the interior cations of the quadruplex by source collision‐induced dissociation (CID) in the positive ion mode showed that the presence of the inner cations is essential for the fast exchange to be possible. Molecular dynamics simulations show that the G‐quadruplex is very rigid in the gas phase with NH 4 +ions inside the tetrads. We suggest that the fast H/D exchange is favored by this rigid quadruplex conformation. This example illustrates that the concept that compact DNA structures exchange H for D slower than unfolded ones is a misconception. Copyright © 2004 John Wiley & Sons, Ltd.