Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin.
The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier.
Department of Bioscience and Bioinformatics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan. imai@is.ritsumei.ac.jp
Takashi
T
Imai
Shusaku
S
Ohyama
Andriy
A
Kovalenko
Fumio
F
Hirata
D006874:Hydrostatic Pressure; D008958:Models, Molecular; D008962:Models, Theoretical; D011487:Protein Conformation; D011489:Protein Denaturation; D013816:Thermodynamics; D025801:Ubiquitin / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D025801:Ubiquitin; D014867:Water