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Eu3+ as a luminescence probe in DNA studies: Structural and conformational implications
1Institute of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo nám, 2, 16610 Prague, Czech Republic.
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|February 10, 2019
Summary
Europium ions (Eu3+) can alter DNA structure, causing base unstacking and backbone changes, even at common luminescence study concentrations. Understanding these effects is crucial for accurate DNA structural analysis using Eu3+ probes.
Area of Science:
- Biochemistry
- Biophysics
- Spectroscopy
Background:
- Lanthanide ions, particularly Europium (Eu3+), are vital luminescent probes for biomolecular structural studies, including DNA.
- Advancements in circularly polarized luminescence (CPL) have increased interest in luminescence techniques for structural biology.
- The impact of lanthanide probes on DNA structure and conformation remains incompletely understood.
Purpose of the Study:
- To investigate the effects of Europium ions (Eu3+) on the structure and conformation of native double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA).
- To compare Eu3+ interactions with dsDNA versus ssDNA using detailed spectroscopic methods.
- To identify Eu3+ binding sites and determine concentrations that preserve DNA geometry for reliable luminescence studies.
Main Methods:
- Infrared (IR) spectroscopy to analyze molecular vibrations and structural changes.
- Vibrational Circular Dichroism (VCD) spectroscopy to probe chiral molecular structures.
- Electronic Circular Dichroism (ECD) spectroscopy to study electronic transitions and DNA conformation.
Main Results:
- Eu3+ ions induce significant structural alterations in native DNA at typical luminescence concentrations, including base unstacking and backbone disordering.
- Observed conformational changes include partial adoption of A-form geometry and transition to a condensed ψ-type form, without causing denaturation.
- Eu3+ exhibits stronger binding to ssDNA compared to dsDNA, with specific binding sites identified.
Conclusions:
- Eu3+ ions significantly impact DNA structure and conformation, necessitating careful consideration of ion concentration in luminescence and CPL studies.
- The study identified critical Eu3+ concentration ranges where DNA geometry is minimally affected, aiding in probe selection.
- Findings provide essential guidance for optimizing Eu3+-based luminescence and CPL techniques for accurate DNA structural investigations.
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