Fluorescence polarization assay to quantify protein-protein interactions: an update

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Protein-protein interactions are crucial for cellular functions.
• Quantifying the strength of these interactions is essential for understanding biological processes.
• Existing methods may have limitations in homogeneous aqueous environments.

Purpose of the Study:

• To develop and demonstrate a fluorescence polarization assay for evaluating protein-protein interaction strength.
• To determine the equilibrium dissociation constant of protein complexes in a homogeneous aqueous environment.
• To provide a robust method for studying biomolecular interactions.

Main Methods:

• A green fluorescent protein variant was fused to one protein partner.
• Complex formation was detected by an increase in fluorescence polarization.
• The equilibrium dissociation constant (Kd) was determined using the assay.

Main Results:

• The fluorescence polarization assay successfully detected complex formation.
• The assay allowed for the determination of the equilibrium dissociation constant.
• The interaction between S-protein and S-peptide fragments of ribonuclease A served as a validated case study.

Conclusions:

• Fluorescence polarization offers a sensitive method for quantifying protein-protein interaction strength.
• This assay is suitable for homogeneous aqueous environments.
• The developed assay provides a valuable tool for biochemical and biophysical research.