Thiophilic interaction chromatography for supercoiled plasmid DNA purification

Area of Science:

• Biochemistry
• Chromatography
• Molecular Biology

Background:

• Plasmid DNA purification is crucial for gene therapy and DNA vaccines.
• Existing methods face challenges in separating supercoiled plasmid DNA from open circular forms and contaminants.
• Thiophilic interaction chromatography offers a potential solution for selective DNA purification.

Purpose of the Study:

• To optimize thiophilic interaction chromatography for selective purification of supercoiled plasmid DNA.
• To identify optimal aromatic thioether ligands for separating plasmid DNA isoforms.
• To evaluate the efficacy of the developed method for isolating high-purity plasmid DNA.

Main Methods:

• Coupling various aromatic thioether ligands to a chromatographic support.
• Screening ligands for their ability to separate supercoiled plasmid DNA from open circular forms and contaminants (RNA, genomic DNA, protein, endotoxins).
• Utilizing high concentrations of water-structuring salts during chromatography.

Main Results:

• Ligand structure significantly influenced the selectivity and resolution of plasmid DNA isoforms.
• Aromatic thioethers with highly electronegative substituents provided optimal resolution.
• 4-nitrothiophol ligand demonstrated superior performance, achieving a 20 mS/cm conductivity difference for plasmid DNA separation, compared to 6 mS/cm for 2-mercaptopyridine.
• Combined with a prior separation step, the method yielded highly purified supercoiled plasmid DNA.

Conclusions:

• Aromatic thioether ligands are effective for selective supercoiled plasmid DNA purification via thiophilic interaction chromatography.
• The developed method provides a robust approach for isolating plasmid DNA suitable for therapeutic and vaccine applications.
• Optimization of ligand structure is key to achieving high-resolution separation of DNA isoforms.