The specific volume of dry protein

Area of Science:

• Biophysics
• Biochemistry
• Materials Science

Background:

• Accurate measurement of dry protein volume is essential for interpreting electron microscopy data.
• Existing methods may not fully capture the intrinsic volume of protein molecules in a dry state.

Purpose of the Study:

• To describe a helium gas pycnometer method for measuring the specific volume of dry protein powders.
• To report measurements of dry protein volumes for common proteins.

Main Methods:

• Utilized a helium gas pycnometer, employing helium as the fluid medium for precise volume displacement measurements.
• Tested dry protein powders including lysozyme, ovalbumin, bovine serum albumin, and fibrinogen.

Main Results:

• Reported specific volume measurements for four different dry protein powders.
• Observed that helium pycnometry values for dry proteins were, on average, 1.4% higher than solution-based measurements (uncorrected for electrostriction).

Conclusions:

• Helium gas pycnometry offers a reliable method for determining the specific volume of dry protein powders.
• The findings highlight potential discrepancies between dry and solution-based volume measurements, emphasizing the importance of considering the measurement state.