Fluorescence Anisotropy Applied to Measure Aptamer-Protein Interactions

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysical Chemistry

Background:

• Quantifying biomolecular binding affinities is crucial for understanding molecular interactions.
• Nucleic acid aptamers offer specific binding capabilities for protein targets.
• Fluorescence anisotropy is a sensitive biophysical technique for monitoring molecular interactions.

Purpose of the Study:

• To describe a fluorescence anisotropy-based method for determining the binding affinity between nucleic acid aptamers and protein targets.
• To provide a detailed protocol for this method, using the thrombin-binding aptamer (TBA)-thrombin system as an example.
• To highlight the broad applicability of this method for various protein-nucleic acid interactions.

Main Methods:

• Fluorescently labeling a nucleic acid aptamer.
• Titrating the labeled aptamer with increasing concentrations of its target protein.
• Monitoring changes in fluorescence anisotropy to generate binding isotherms and calculate the dissociation constant (K_D).

Main Results:

• The fluorescence anisotropy method accurately quantifies the binding affinity (K_D) between the thrombin-binding aptamer (TBA) and thrombin.
• The protocol provides detailed steps for reagent preparation, plate setup, data acquisition, and analysis.
• Emphasis is placed on minimizing experimental variability for reliable results.

Conclusions:

• Fluorescence anisotropy is a rapid, sensitive, and accurate technique for quantifying aptamer-protein binding affinities.
• The described method is broadly applicable to diverse nucleic acid-protein interaction studies.
• This protocol facilitates the characterization of biomolecular binding interactions.