Using Electrospray Ionization Mass Spectrometry to Explore the Interactions Among Polythymine Oligonucleotides, Ethidium Bromide, and Mercury Ions

Cheng Kang Chiang, Yang Wei Lin, Cho Chun Hu, Huan Tsung Chang

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We have used electrospray ionization mass spectrometry (ESI-MS) and fluorescence and circular dichroism (CD) spectroscopy to explore the binding of ethidium bromide (EthBr) to non-self-complementary polythymine (polyT) strands in the absence and presence of Hg2+ ions. In the gas phase, ESI-MS revealed that Hg2+ ions have greater affinity, through T-Hg2+-T coordination, toward polyT strands than do other metal ions. These findings are consistent with our fluorescence and CD results obtained in solution; they revealed that more T33-EthBr-Hg2+ complexes existed upon increasing the concentrations of Hg2+ ions (from 0 to 50 μM). Surprisingly, the ESI-MS data indicated that the Hg2+ concentration dependence of the interaction between T33 and EthBr is biphasic. Our ESI-MS data revealed that the T33-EthBr-Hg2+ complexes formed with various stoichiometries depending on their relative concentrations of the components and the length of the DNA strand. When the concentrations of T33/EthBr/Hg2+ were 5/5/2.5 μM and 5/10/7.5 μM, 1:1:1 and 1:1:2 T33-EthBr-Hg2+ complexes were predominantly formed, respectively. Thus, Hg2+-induced DNA conformational changes clearly affect the interactions between DNA and EthBr.

Original languageEnglish
Pages (from-to)1834-1840
Number of pages7
JournalJournal of the American Society for Mass Spectrometry
Volume20
Issue number10
DOIs
Publication statusPublished - 2009 Oct 1

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Spectroscopy

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