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Stability analysis for double‐stranded DNA oligomers and their noncovalent complexes with drugs by laser spray
Author(s) -
Shi Xiangguo,
Takamizawa Atsushi,
Nishimura Yoshifumi,
Hiraoka Kenzo,
Akashi Satoko
Publication year - 2006
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.1069
Subject(s) - chemistry , netropsin , minor groove , dna , laser , mass spectrometry , affinities , analytical chemistry (journal) , stereochemistry , crystallography , chromatography , biochemistry , physics , optics
Laser spray, which is a newly developed ionization technique, can characterize the stability of noncovalent complexes in the solution phase. By using this advantage, laser spray has been applied to probe the intrinsic stability of double‐stranded DNA (dsDNA) sequences and their binding affinities with various drugs in the solution phase. Systematic experiments were carried out using six 16‐mer and three 22‐mer dsDNA oligomers, together with the complexes of the 16‐mer dsDNA with minor groove binders: berenil, Hoechst 33342, DAPI, and netropsin. Dissociation curves for each dsDNA or each complex were plotted as a function of laser power. The laser power ( E 50% ), where 50% of each dsDNA or each complex was dissociated, was compared with its melting temperature ( T m ) determined by UV spectroscopy. Linear correlations between E 50% and T m were obtained not only for the dsDNA oligomers (correlation factor r = 0.9835) but also for the 16‐mer dsDNA complexes with minor groove binders ( r = 0.9966). In addition, laser spray has successfully clarified the binding affinities of a 16‐mer dsDNA with two intercalators: daunomycin and nogalamycin. In the case of the dsDNA–daunomycin complex, by changing the molar ratio of dsDNA : drug from 1 : 1 to 1 : 5, the concentration‐dependent stability of the complex was confirmed by laser spray. The present results demonstrate that laser spray mass spectrometry can be a powerful and convenient method to investigate the relative binding affinities of dsDNA–ligand complexes in the solution phase, which could be applied to the early stage of high‐throughput screening of drugs targeting for dsDNA. Copyright © 2006 John Wiley & Sons, Ltd.