Anal. Chem. 2007, 79, 2067-2077
Infrared Multiphoton Dissociation of Duplex DNA/ Drug Complexes in a Quadrupole Ion Trap Jeffrey J. Wilson and Jennifer S. Brodbelt*
Department of Chemistry and Biochemistry, 1 University Station A5300, University of Texas at Austin, Austin, Texas 78712
Noncovalent duplex DNA/drug complexes formed between one of three 14-base pair non-self-complementary duplexes with variable GC content and one of eight different DNA-interactive drugs are characterized by infrared multiphoton dissociation (IRMPD), and the resulting spectra are compared to conventional collisionally activated dissociation (CAD) mass spectra in a quadrupole ion trap mass spectrometer. IRMPD yielded comparable information to previously reported CAD results in which strand separation pathways dominate for complexes containing the more AT-rich sequences and/ or minor groove binding drugs, whereas drug ejection pathways are prominent for complexes containing intercalating drugs and/or duplexes with higher GC base content. The large photoabsorptive cross section of the phosphate backbone at 10.6 µm promotes highly efficient dissociation within short irradiation times (
