Structural and physicochemical features on the metal-mediated base pairs.

Area of Science:

• Biophysical Chemistry
• Nucleic Acid Chemistry
• Spectroscopy

Background:

• Mercury ions can interact with DNA and RNA.
• Understanding metal-mediated base pairing is essential for nucleic acid structural biology.
• Novel spectroscopic methods are needed to elucidate complex metal-nucleic acid interactions.

Purpose of the Study:

• To determine the chemical structure of the mercury-mediated T-T pair (T-Hg(I)I-T).
• To investigate the utility of (15)N-(15)N J-coupling across a metal center ((2)J(NN)) for structural analysis.
• To characterize a novel metal ion-binding mode in nucleic acids.

Main Methods:

• Utilized (15)N Nuclear Magnetic Resonance ((15)N NMR) spectroscopy.
• Employed (15)N-(15)N J-coupling across a metal center ((2)J(NN)) for structural determination.
• Analyzed mercury-mediated thymine-thymine (T-T) pairs within a DNA duplex context.

Main Results:

• Successfully determined the chemical structure of the T-Hg(I)I-T pair.
• Achieved the first observation of (2)J(NN) coupling in a biological macromolecule (DNA duplex).
• Identified an irregular metal ion-binding mode involving imino proton-metal exchange in DNA and RNA.

Conclusions:

• The (2)J(NN) coupling is a powerful tool for determining the chemical structures of metal-mediated base pairs.
• This study expands the understanding of diverse metal ion-binding modes in nucleic acids.
• The findings have implications for understanding metal interactions in biological systems and developing novel therapeutic strategies.