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Related Experiment Video

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In Vitro Chemical Mapping of G-Quadruplex DNA Structures by Bis-3-Chloropiperidines

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Interaction of isoquinoline alkaloids with polymorphic DNA structures.

Kakali Bhadra¹, Motilal Maiti, Gopinatha Suresh Kumar

¹Biophysical Chemistry Laboratory, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S.C. Mullick Road, Kolkata 700032, India. kakalibhadra_rs@iicb.res.in

Chemistry & Biodiversity

|September 24, 2009

Summary

Isoquinoline alkaloids like berberine, palmatine, and coralyne interact differently with various DNA forms. Coralyne shows strong binding to Z DNA and H(L) DNA, while berberine binds cooperatively to H(L) DNA.

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Area of Science:

Biochemistry
Molecular Biology
Structural Biology

Background:

Isoquinoline alkaloids are a class of natural compounds with diverse biological activities.
DNA can exist in various polymorphic forms (B, Z, H(L)) depending on sequence and environmental conditions.
Understanding small molecule-DNA interactions is crucial for drug development and molecular biology.

Purpose of the Study:

To investigate the binding interactions of berberine, palmatine, and coralyne with different polymorphic forms of poly[d(G-C)] DNA.
To elucidate the thermodynamic and spectroscopic basis of these interactions.
To correlate the structural features of isoquinoline alkaloids with their DNA binding affinities and modes.

Main Methods:

Spectroscopic techniques (e.g., UV-Vis, Circular Dichroism) were used to monitor binding.
Thermodynamic studies (e.g., isothermal titration calorimetry) were employed to determine binding parameters.
Analysis of binding data to assess affinity, stoichiometry, and thermodynamic driving forces.

Main Results:

Berberine and palmatine exhibited moderate binding to B-DNA, while coralyne showed higher affinity.
Coralyne demonstrated strong binding to Z-DNA, whereas berberine and palmatine did not bind or alter this form.
Berberine displayed cooperative binding to H(L)-DNA, forming an induced CD band, while palmatine showed weak and coralyne strong binding to this form.
Binding to B-DNA was exothermic and enthalpy-driven for berberine and coralyne; palmatine binding was exothermic and favored by negative enthalpy and entropy.

Conclusions:

The structural variations among isoquinoline alkaloids significantly influence their binding affinity and interaction mechanisms with polymorphic DNA structures.
Coralyne shows a notable preference for Z-DNA and H(L)-DNA, suggesting potential for targeted therapeutic applications.
The distinct binding modes highlight the importance of DNA conformation in dictating drug-target interactions.