title: Specific volume and adiabatic compressibility measurements of native and aggregated recombinant human interleukin-1 receptor antagonist: density differences enable pressure-modulated refolding.
abstract: High hydrostatic pressures have been used to dissociate non-native protein aggregates and foster refolding to the native conformation. In this study, partial specific volume and adiabatic compressibility measurements were used to examine the volumetric contributions to pressure-modulated refolding. The thermodynamics of pressure-modulated refolding from non-native aggregates of recombinant human interleukin-1 receptor antagonist (IL-1ra) were determined by partial specific volume and adiabatic compressibility measurements. Aggregates of IL-1ra formed at elevated temperatures (55 degrees C) were found to be less dense than native IL-1ra and refolded at 31 degrees C under 1,500 bar pressure with a yield of 57%. Partial specific adiabatic compressibility measurements suggest that the formation of solvent-free cavities within the interior of IL-1ra aggregates cause the apparent increase in specific volume. Dense, pressure-stable aggregates could be formed at 2,000 bar which could not be refolded with additional high pressure treatment, demonstrating that aggregate formation conditions and structure dictate pressure-modulated refolding yields.
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Seefeldt
authors.forename: Chris
authors.initials: C
authors.lastname: Crouch
authors.forename: Brent
authors.initials: B
authors.lastname: Kendrick
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Randolph
mesh_terms: D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein / Q000737:chemistry* / Q000302:isolation & purification; D008968:Molecular Conformation; D011312:Pressure; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D053590:Interleukin 1 Receptor Antagonist Protein; D011994:Recombinant Proteins