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Molecular confinement influences protein structure and enhances thermal protein stability
Author(s) -
Eggers Daryl K.,
Valentine Joan S.
Publication year - 2001
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.36201
Subject(s) - chemistry , circular dichroism , ionic strength , macromolecule , macromolecular crowding , thermal stability , hofmeister series , lysozyme , crystallography , protein aggregation , steric effects , protein structure , protein folding , biophysics , ionic bonding , chemical engineering , aqueous solution , stereochemistry , organic chemistry , ion , biochemistry , engineering , biology
The sol‐gel method of encapsulating proteins in a silica matrix was investigated as a potential experimental system for testing the effects of molecular confinement on the structure and stability of proteins. We demonstrate that silica entrapment (1) is fully compatible with structure analysis by circular dichroism, (2) allows conformational studies in contact with solvents that would otherwise promote aggregation in solution, and (3) generally enhances thermal protein stability. Lysozyme, α‐lactalbumin, and metmyoglobin retained native‐like solution structures following sol‐gel encapsulation, but apomyoglobin was found to be largely unfolded within the silica matrix under control buffer conditions. The secondary structure of encapsulated apomyoglobin was unaltered by changes in pH and ionic strength of KCl. Intriguingly, the addition of other neutral salts resulted in an increase in the α‐helical content of encapsulated apomyoglobin in accordance with the Hofmeister ion series. We hypothesize that protein conformation is influenced directly by the properties of confined water in the pores of the silica. Further work is needed to differentiate the steric effects of the silica matrix from the solvent effects of confined water on protein structure and to determine the extent to which this experimental system mimics the effects of crowding and confinement on the function of macromolecules in vivo.