Investigating the effect of transition metal ion oxidation state on oligodeoxyribonucleotide binding by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry

✍ Scribed by Robert L. Hettich

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 659 KB
• Volume: 204
• Category: Article
• ISSN: 1387-3806
• DOI: 10.1016/s1387-3806(00)00338-9

✦ Synopsis

Investigations of the interactions of metals with nucleotides and oligonucleotides are important for a variety of areas, including understanding nucleic acid metabolism and ability of the metals to stabilize or destablize the double-stranded helix of DNA. This report illustrates the application of matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry for the study of the fundamental interactions of metal ions with small, single-stranded oligonucleotides, with a specific focus on evaluation of sequential metal ion attachment and binding site(s) determination. Whereas incorporation of Cu (I) into dinucleotides reveals the maximum number of protons that can be replaced by singly charged metal ions, incorporation of iron (II, III) into the same biomolecules is sensitive to steric binding factors as well. These results suggest a mechanism in which complexes of the metal ion and the laser matrix compound (2,5-dihydroxybenzoic acid, or DHB) coordinate with the oligonucleotides and attach metal ions by eliminating neutral DHB molecules. Ions of divalent (Zn 2ϩ , Fe 2ϩ ), trivalent (Fe 3ϩ , Ce 3ϩ ), and tetravalent (Ce 4ϩ , Th 4ϩ ) metals all bind strongly to oligonucleotides and are retained even in the fragment ions. Based on high-resolution mass measurements and fragmentation information, structures are proposed for these gas phase species in which the metal ion coordination to the oligonucleotide involves both phosphate and nucleobase interactions. These studies provide molecular level information about metal ion interactions with oligonucleotides, and may be the basis for determining how certain metal ions can be exploited as selective probes for biomolecular structure interrogation. (Int J Mass Spectrom 204 (2001) 55-75) © 2001 Elsevier Science B.V.