Low crowding agent concentration destabilizes against pressure unfolding.

Area of Science:

• Biochemistry
• Cell Biology
• Biophysics

Background:

• High intracellular macromolecule concentrations, known as macromolecular crowding, significantly influence enzyme activity and biological processes.
• The excluded volume effect is a primary consequence of macromolecular crowding, impacting molecular interactions and stability.
• Understanding these effects is crucial for comprehending cellular function and protein behavior in vivo.

Purpose of the Study:

• To investigate the impact of macromolecular crowding on protein stability under varying pressure conditions.
• To analyze the role of excluded volume and hydration changes in protein stability within crowded cellular environments.
• To quantify the pressure and temperature stability of specific proteins (bovine serum albumin and lysozyme) in the presence of different crowding agents.

Main Methods:

• Performed pressure-volume experiments to assess protein stability.
• Utilized various crowding agents including dextran, Ficoll™, and lysozyme at different concentrations.
• Measured temperature and pressure stability of bovine serum albumin and lysozyme.

Main Results:

• A key finding is that low concentrations of all tested crowding agents reduced protein pressure stability.
• This decrease in stability is attributed to a reduced hydration volume change in the crowded environment.
• The study highlights the complex relationship between excluded volume, partial protein volume, and influenced volume.

Conclusions:

• Macromolecular crowding has a non-intuitive effect on protein pressure stability, particularly at low crowding agent concentrations.
• Hydration dynamics play a critical role in mediating the effects of excluded volume on protein stability.
• The findings provide insights into the volumetric parameters governing protein behavior in crowded biological systems.