DropFit: Determination of the Critical Concentration for Protein Liquid-Liquid Phase Separation

Area of Science:

• Biochemistry and Biophysics
• Molecular Biology
• Cell Biology

Background:

• Liquid-liquid phase separation (LLPS) of proteins forms dense droplets below a critical concentration.
• Droplet size distribution follows a scale-invariant pattern, useful for critical concentration estimation.
• Accurate critical concentration is vital for understanding protein condensate formation and function.

Purpose of the Study:

• To present the DropFit web server for quantitative estimation of protein critical concentration.
• To provide a user-friendly tool for analyzing experimental data on precritical droplets.
• To facilitate research on protein condensates and their role in biological processes and diseases.

Main Methods:

• Utilizing the scale-invariant size distribution of precritical droplets below the critical concentration.
• Employing experimental data on droplet length, area, or volume.
• Developing the DropFit web server for accessible data analysis.

Main Results:

• DropFit enables accurate and reproducible estimation of critical concentration from experimental data.
• The web server simplifies the application of droplet size distribution analysis for critical concentration determination.
• Validated the utility of DropFit for quantitative analysis of protein LLPS.

Conclusions:

• DropFit facilitates accurate critical concentration measurement, crucial for studying protein condensates.
• Understanding critical concentration aids in elucidating macromolecular contributions to condensate formation.
• This tool can help investigate pathological processes linked to membraneless organelle dysfunction.