Formation and Characterization of Protein Solid-like Phases

Soft matter and complex fluid behavior are of great interest to numerous industrial efforts, notably in food and pharmaceutical processing. Protein-derived materials can be extremely sensitive to temperature and pH variations, which presents a significant challenge in processing and stabilizing these materials while preserving material properties of interest [1,4]. High pressure (HP) is used to increase product shelf-life or confer desired properties, particularly in applications in which thermal processing can shift phase behavior in undesirable ways. HP is also present during freezing and utilized to assist in foaming processes, yet relatively little is known about its effects on the macromolecular level. The present work explores pressure effects on solutions of globular proteins in the presence of concentrated salt, which has been well-documented to induce protein clustering, gelation, and liquid-liquid phase separation (LLPS) at ambient conditions, as well as food biopolymers known to behave thermorheologically [1, 3]. Small-angle neutron and x-ray scattering (SANS, SAXS) as well as static light scattering (SLS) are utilized to study the microstructural influences of pressure on the protein particles and dense phases, while bulk rheology and microrheology are performed to reveal the corresponding mechanical response to pressure. The goal of this work is to expand the current knowledge base of protein biophysics with respect to pressure-directed phase behavior, with the potential to inform new pathways in industrial processing for achieving and maintaining desired material properties [2,4].

References

[1] Beck, C.; Grimaldo, M.; Braun, M. K.; Bühl, L.; Matsarskaia, O.; Jalarvo, N. H.; Zhang, F.; Roosen-Runge, F.; Schreiber, F.; Seydel, T., Temperature and salt controlled tuning of protein clusters. Soft Matter 2021, 17 (37), 8506-8516.

[2] Dennis, K. A.;  Gao, Y.;  Phatak, A.;  Sullivan, P. F.; Furst, E. M., Design, operation, and validation of a microrheology instrument for high-pressure linear viscoelasticity measurements. Journal of Rheology 2020, 64 (1), 205-212.

[3] Greene, D. G.; Modla, S.; Sandler, S. I.; Wagner, N. J.; Lenhoff, A. M., Nanocrystalline protein domains via salting-out. Acta Crystallographica Section F Structural Biology Communications 2021, 77 (11), 412-419.

[4] Teixeira, S. C. M., High-pressure small-angle neutron scattering for food studies. Current Opinion in Colloid & Interface Science 2019, 42, 99-109.