title: Microscopic Origin of Hysteresis in Water Sorption on Protein Matrices.
abstract: Despite the importance of water sorption isotherms for a fundamental understanding of protein-water interactions, the microscopic origin of hysteresis between the adsorption and desorption branches is not well understood. Using our recently developed simulation technique, we compute the water sorption isotherms of two proteins, lysozyme and Trp-cage, a miniprotein. We explicitly compare protein-water interactions in adsorption and desorption processes, by analyzing local hydration in terms of hydrogen bonding, water density, and solvent-accessible surface area. We find that significant differences in hydration behavior between adsorption and desorption manifest themselves at the individual amino acid level, in particular around polar or charged residues. We confirm this observation by demonstrating that Trp-cage's hysteresis can be significantly reduced by mutating charged residues to alanine, a neutral and nonpolar amino acid.
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Sang Beom
authors.initials: SB
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Evan M
authors.initials: EM
authors.lastname: Sparano
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Rakesh S
authors.initials: RS
authors.lastname: Singh
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Pablo G
authors.identifier: http://orcid.org/0000-0003-1881-1728
authors.initials: PG
authors.lastname: Debenedetti
mesh_terms: D000327:Adsorption; D006860:Hydrogen Bonding; D009113:Muramidase / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D010455:Peptides; D011506:Proteins; C508725:Trp-cage peptide; D014867:Water; D009113:Muramidase