Intercalation interactions between dsDNA and acridine studied by single molecule force spectroscopy.

Area of Science:

• Biophysics
• Molecular Biology
• Chemical Biology

Background:

• Acridine derivatives are known DNA intercalators with applications in medicine.
• Understanding the precise binding and unbinding mechanisms of these molecules to DNA is crucial for drug development.
• Direct force measurements provide quantitative insights into molecular interactions at the single-molecule level.

Purpose of the Study:

• To directly measure the intercalation forces between acridine and double-stranded DNA (dsDNA).
• To investigate the dynamic nature of acridine-dsDNA binding.
• To identify energy landscapes governing the unbinding process.

Main Methods:

• Single Molecule Force Spectroscopy (SMFS) was employed to apply controlled force.
• Acridine-dsDNA interactions were probed by applying force until rupture.
• Loading rate dependence of rupture force was analyzed.
• Experimental data was integrated with theoretical models.

Main Results:

• The acridine-dsDNA interaction rupture force was measured at 36 pN under a 5.0 nN/s loading rate.
• Rupture force exhibited dependence on the loading rate, indicating a dynamic binding process.
• Analysis revealed the presence of two distinct energy barriers in the acridine-dsDNA unbinding pathway.

Conclusions:

• Direct force measurements confirm the dynamic nature of acridine intercalation into dsDNA.
• The identified energy barriers provide a detailed map of the unbinding trajectory.
• This study offers a quantitative understanding of acridine-DNA interactions, relevant for pharmaceutical applications.