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A single cyclic p-benzoquinone adduct can destabilize a DNA oligonucleotide duplex
1Donner Laboratory, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA.
Chemical Research in Toxicology
|May 5, 1998
Summary
p-Benzoquinone (p-BQ) adducts with DNA bases significantly reduce duplex stability, comparable to double mismatches. These findings offer insights into DNA damage and repair mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Chemical Biology
Background:
- p-Benzoquinone (p-BQ) is a benzene metabolite forming adducts with DNA bases.
- These adducts can influence DNA structure and function, potentially leading to mutations.
Purpose of the Study:
- To biophysically characterize DNA duplexes with site-specific p-BQ-C adducts.
- To understand the impact of p-BQ-C adducts on DNA thermal and thermodynamic stability.
Main Methods:
- Thermal denaturation analysis to determine melting temperature (Tm) and thermodynamic stability (ΔG°).
- Circular dichroism (CD) spectroscopy to assess conformational changes.
Main Results:
- p-BQ-C adducts significantly reduced duplex thermal stability (Tm decreased by 12.6°C) and thermodynamic stability (ΔG° by 10.2 kcal/mol).
- The destabilization effect was comparable to double base mismatches and independent of the opposite base.
- CD spectra indicated only minor alterations to the overall B-conformation.
Conclusions:
- p-BQ-C adducts substantially destabilize DNA duplexes.
- The observed thermodynamic and conformational changes are similar to those in abasic sites, suggesting related repair pathway involvement.