Peptide Nucleic Acids Containing Cationic/Amino-Alkyl Modified Bases Promote Enhanced Hybridization Kinetics and...

Area of Science:

• Oligonucleotide chemistry
• Biophysical chemistry
• Antisense technology

Background:

• Peptide nucleic acids (PNAs) are effective antisense molecules but suffer from poor cell permeability.
• Cationic substitutions can improve PNA cell permeability and activity.

Purpose of the Study:

• To synthesize and characterize a novel cationic/amino-alkyl base-modified PNA (OPNA).
• To quantify the impact of these modifications on OPNA-DNA hybridization kinetics and thermodynamics.

Main Methods:

• Surface Plasmon Resonance (SPR) for kinetic analysis.
• UV thermal melt studies for thermodynamic analysis.

Main Results:

• Single cationic modifications increased OPNA-DNA binding affinity 10-30 fold by improving association and decreasing dissociation rates.
• Additional amino-alkyl modifications further reduced dissociation rates (3-10 fold per modification).
• A favorable enthalpy change of -80 kJ/mol per amino-alkyl modification suggests ion-ion interactions.

Conclusions:

• Cationic/amino-alkyl base modification significantly enhances PNA hybridization properties.
• These modified PNAs (OPNAs) demonstrate favorable kinetics and thermodynamics for antisense applications.