Related Experiment Video
Updated: Aug 11, 2026

Mass Spectrometric Approaches to Study Protein Structure and Interactions in Lyophilized Powders
Published on: April 14, 2015
Long-term and high-temperature storage of supercritically-processed microparticulate protein powders
M A Winters1, P G Debenedetti, J Carey
1Department of Chemical Engineering, Princeton University, New Jersey 08544-5263, USA.
Purpose:
The long-term and high-temperature storage of dry, micron-sized particles of lysozyme, trypsin, and insulin was investigated. Subsequent to using supercritical carbon dioxide as an antisolvent to induce their precipitation from a dimethylsulfoxide solution, protein microparticles were stored in sealed containers at -25, -15, 0, 3, 20, 22, and 60 degrees C. The purpose of this study was to investigate the suitability of supercritical antisolvent precipitation as a finishing step in protein processing.
Methods:
Karl Fisher titrations were used to determine the residual moisture content of commercial and supercritically-processed protein powders. The secondary structure of the dry protein particles was determined periodically during storage using Raman spectroscopy. The proteins were also redissolved periodically in aqueous buffers and assayed spectrophotometrically for biological activity and by circular dichroism for structural conformation in solution.
Results:
Amide I band Raman spectra indicate that the secondary structure of the protein particles, while perturbed from that of the solution state, remained constant in time, regardless of the storage temperature. The recoverable biological activity upon reconstitution for the supercritically-processed lysozyme and trypsin microparticles was also preserved and found to be independent of storage temperature. Far UV circular dichroism spectra support the bioactivity assays and further suggest that adverse structural changes, with potential to hinder renaturation upon redissolution, do not take place during storage.
Conclusions:
The present study suggests that protein precipitation using supercritical fluids may yield particles suitable for long-term storage at ambient conditions.
Related Concept Videos
Sample Handling
Samples should be transported carefully from collection points to the laboratory. They should be properly sealed and clearly labeled to prevent cross-contamination. To preserve the sample integrity, optimal temperature conditions during transport are essential. This could involve using...
Physical Methods for Controlling Microbial Growth: Temperature
Pasteurization and Food Preservation
Principles of Food Preservation
Methods of Controlling Food Spoilage

