How fluorescent labelling alters the solution behaviour of proteins

Area of Science:

• Soft matter science
• Biophysics
• Colloidal science

Background:

• Understanding molecular anisotropy's role in self-assembly is crucial for soft matter science and biophysics.
• Protein surface complexity challenges theoretical and numerical descriptions of self-assembly.
• Patchy models offer a soft matter approach to describe protein phase behavior.

Purpose of the Study:

• To investigate the impact of chemical modification (fluorophore addition) on protein solution physical properties.
• To determine if a custom patchy particle model can capture anisotropic surface effects in protein solutions.

Main Methods:

• Utilized a model protein system (human gamma-D crystallin).
• Employed carefully controlled experiments and numerical simulations.
• Developed and applied a custom patchy particle model.

Main Results:

• Chemical modification with a fluorophore is equivalent to adding a large hydrophobic patch with a significant attractive potential.
• This modification substantially increases the liquid-liquid phase separation temperature.
• Even low fractions of fluorescently labeled proteins cause a significant increase in phase separation temperature.

Conclusions:

• Anisotropic surface effects in protein solutions can be effectively modeled using custom patchy particle approaches.
• Fluorophore labeling significantly alters protein solution behavior, particularly phase separation temperature.
• Findings are relevant for applications using fluorescent labeling in biological and biophysical studies.