Back to Search
Start Over
Direct Evidence for the Effect of Glycerol on Protein Hydration and Thermal Structural Transition
- Source :
- Biophysical journal. 115(2)
- Publication Year :
- 2018
-
Abstract
- The mechanisms of protein stabilization by uncharged solutes, such as polyols and sugars, have been intensively studied with respect to the chemical thermodynamics of molecular crowding. In particular, many experimental and theoretical studies have been conducted to explain the mechanism of the protective action on protein structures by glycerol through the relationship between hydration and glycerol solvation on protein surfaces. We used wide-angle x-ray scattering (WAXS), small-angle neutron scattering, and theoretical scattering function simulation to quantitatively characterize the hydration and/or solvation shell of myoglobin in aqueous solutions of up to 75% v/v glycerol. At glycerol concentrations below ∼40% v/v, the preservation of the hydration shell was dominant, which was reasonably explained by the preferential exclusion of glycerol from the protein surface (preferential hydration). In contrast, at concentrations above 50% v/v, the partial penetration or replacement of glycerol into or with hydration-shell water (neutral solvation by glycerol) was gradually promoted. WAXS results quantitatively demonstrated the neutral solvation, in which the replacement of hydrated water by glycerol was proportional to the volume fraction of glycerol in the solvent multiplied by an exchange rate ( β ≤ 1). These phenomena were confirmed by small-angle neutron scattering measurements. The observed WAXS data covered the entire hierarchical structure of myoglobin, ranging from tertiary to secondary structures. We separately analyzed the effect of glycerol on the thermal stability of myoglobin at each hierarchical structural level. The thermal transition midpoint temperature at each hierarchical structural level was raised depending on the glycerol concentration, with enhanced transition cooperativeness between different hierarchical structural levels. The onset temperature of the helix-to-cross β -sheet transition (the initial process of amyloid formation) was evidently elevated. However, oligomerization connected to fibril formation was suppressed, even at a low glycerol concentration.
- Subjects :
- Glycerol
Protein Conformation, alpha-Helical
Biophysics
Neutron scattering
010402 general chemistry
01 natural sciences
chemistry.chemical_compound
0103 physical sciences
Animals
Thermal stability
Aqueous solution
010304 chemical physics
Dose-Response Relationship, Drug
010405 organic chemistry
Chemistry
Myoglobin
Solvation
Temperature
Proteins
Water
Correction
0104 chemical sciences
Solvation shell
Solvents
Physical chemistry
Protein Conformation, beta-Strand
Protein stabilization
Subjects
Details
- ISSN :
- 15420086
- Volume :
- 115
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- Biophysical journal
- Accession number :
- edsair.doi.dedup.....ecb93e426aa9af0ca00cdd08207c4251