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Studies of the intermolecular DNA triplexes of C + ·GC and T·AT triplets by electrospray ionization Fourier‐transform ion cyclotron resonance mass spectrometry
Author(s) -
Wan Cuihong,
Guo Xinhua,
Liu Zhiqiang,
Liu Shuying
Publication year - 2008
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1277
Subject(s) - chemistry , fourier transform ion cyclotron resonance , electrospray ionization , dissociation (chemistry) , mass spectrometry , analytical chemistry (journal) , ion cyclotron resonance , intermolecular force , mass spectrum , ion , hydrogen bond , crystallography , molecule , chromatography , organic chemistry , cyclotron
Formation and stabilities of four 14‐mer intermolecular DNA triplexes, consisting of third strands with repeating sequence CTCT, CCTT, CTT, or TTT, were studied by electrospray ionization Fourier‐transform ion cyclotron resonance mass spectrometry (ESI‐FTICR‐MS) in the gas phase. The gas‐phase stabilities of the triplexes were compared with their CD spectra and melting behaviors in solution, and parallel correlation between two phases were obtained. In the presence of 20 m M NH 4 + (pH 5.5), the formation of the TTT triplex was not detected in both solution and the gas phase. Other triplexes showed the same order, CTCT > CCTT > CTT, of ion abundances in mass spectra and T m values in solution. The more stable triplexes are those that contained higher percentage of C + ·GC triplets and an alternating CT sequence. However, the CCTT with the same C + ·GC triplets as the CTCT showed a higher stability than the latter during the gas‐phase dissociation. Furthermore, a biphasic triplex‐to‐duplex‐to‐single transition was detected in the gas phase, while a monophasic triplex‐to‐single dissociation was observed in solution. The present results reveal that hydrogen bonds and electrostatic interactions dominate in the gas phase, while base stacking and hydrophobic interactions dominate in solution to stabilize the triplexes. Moreover, weak acidic conditions (pH 5–6) promote the formation of the parallel triplexes. Copyright © 2007 John Wiley & Sons, Ltd.