Protein-protein interactions in concentrated electrolyte solutions.
Protein-protein interactions were measured for ovalbumin and for lysozyme in aqueous salt solutions. Protein-protein interactions are correlated with a proposed potential of mean force equal to the free energy to desolvate the protein surface that is made inaccessible to the solvent due to the protein-protein interaction. This energy is calculated from the surface free energy of the protein that is determined from protein-salt preferential-interaction parameter measurements. In classical salting-out behavior, the protein-salt preferential interaction is unfavorable. Because addition of salt raises the surface free energy of the protein according to the surface-tension increment of the salt, protein-protein attraction increases, leading to a reduction in solubility. When the surface chemistry of proteins is altered by binding of a specific ion, salting-in is observed when the interactions between (kosmotrope) ion-protein complexes are more repulsive than those between the uncomplexed proteins. However, salting-out is observed when interactions between (chaotrope) ion-protein complexes are more attractive than those of the uncomplexed proteins.
Chemical Engineering Department, University of California, Berkeley, 94720, USA.
R A
RA
Curtis
J
J
Ulrich
A
A
Montaser
J M
JM
Prausnitz
H W
HW
Blanch
D003198:Computer Simulation; D004563:Electrochemistry; D004573:Electrolytes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008956:Models, Chemical; D008970:Molecular Weight; D009113:Muramidase / Q000737:chemistry*; D009994:Osmolar Concentration; D010047:Ovalbumin / Q000737:chemistry*; D011487:Protein Conformation; D025941:Protein Interaction Mapping / Q000379:methods*; D012492:Salts / Q000737:chemistry; D012680:Sensitivity and Specificity; D012996:Solutions; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D004573:Electrolytes; D046911:Macromolecular Substances; D012492:Salts; D012996:Solutions; D014867:Water; D010047:Ovalbumin; D009113:Muramidase