Characterization of Modified Nucleic Acid Constituents by Matrix-Assisted Laser Desorption Mass Spectrometry

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is being developed for the sensitive detection (pmol-fmol) and structural characterization of modified nucleosides, nucleotides, and oligonucleotides. Two types of mass spectrometers are being used for these studies: 1) Fourier transform mass spectrometry (FTMS), which provides high resolution, accurate mass measurement, and ion manipulation capabilities for studying ionic structures, and 2) time-of-flight (TOF) mass spectrometry, which has a wide mass range and is suitable for the study of variables affecting ion formation by the laser desorption process. Both of these techniques are being used to develop MALDI methods for the examination of underivatized, polar biomolecules of biological interest, such as DNA adducts. The objective of this report is to demonstrate the applicability of this technique for the detailed characterization of polycyclic aromatic hydrocarbon adducts of nucleosides and nucleotides.