Molecular-Level Insight of the Effect of Hofmeister Anions on the Interfacial Surface Tension of a Model Protein.
The effect of the Hofmeister anions on the precipitation of proteins is often discussed using liquid-vapor coexisting systems with the assumption that the liquid-vapor interface mimics the liquid-protein interface. Solvated proteins, however, have both hydrophobic and hydrophilic regions on their surfaces rather than just a pure hydrophobic one. Using a solvated parallel β-sheet layer consisting of both hydrophobic and positively charged hydrophilic surfaces, we investigated the adsorption of kosmotropic (SO42-) and chaotropic (ClO4-) anions toward the protein's hydrophobic and hydrophilic surfaces via Born-Oppenheimer molecular dynamics simulations using the BLYP density functional theory. It was found that both anions prefer to reside on the hydrophilic surface. Furthermore, kosmotropic anions, like SO42-, enhance the interfacial surface tension of the protein and stabilize the protein, whereas, in contrast, chaotropic anions, like ClO4-, weaken the interfacial surface tension of the protein and allow water molecules to penetrate toward the peptide bonds to form water-peptide hydrogen bonds, thus destabilizing the protein.
Department of Micro/Nano-electronics, Shanghai Jiao Tong University , 800 Dong Chuan Road, Shanghai 200240, People's Republic of China.
Soohaeng Yoo
http://orcid.org/0000-0001-8830-4487
SY
Willow
Physical Sciences Division, Pacific Northwest National Laboratory , 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States.
Sotiris S
SS
Xantheas
D000327:Adsorption; D000838:Anions; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D013500:Surface Tension; D014867:Water / Q000737:chemistry
D000838:Anions; D010455:Peptides; D011506:Proteins; D014867:Water