title: Cooperative hydration effect causes thermal unfolding of proteins and water activity plays a key role in protein stability in solutions.
abstract: The protein unfolding process observed in a narrow temperature range was clearly explained by evaluating the small difference in the enthalpy of hydrogen-bonding between amino acid residues and the hydration of amino acid residue separately. In aqueous solutions, the effect of cosolute on the protein stability is primarily dependent on water activity, aw, the role of which has been long neglected in the literature. The effect of aw on protein stability works as a power law so that a small change in aw is amplified substantially through the cooperative hydration effect. In the present approach, the role of hydrophobic interaction stands behind. This affects protein stability indirectly through the change in solution structure caused by the existence of cosolute.
authors.affiliation: Department of Food Science, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan. Electronic address: osato@ishikawa-pu.ac.jp.
authors.forename: Osato
authors.initials: O
authors.lastname: Miyawaki
authors.affiliation: Department of Food Science, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Dozen
authors.affiliation: Department of Food Science, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan.
authors.forename: Kaede
authors.initials: K
authors.lastname: Hirota
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002417:Cattle; D002645:Chickens; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D011489:Protein Denaturation; D055550:Protein Stability; D058767:Protein Unfolding; D011506:Proteins / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D011506:Proteins; D012996:Solutions; D014867:Water
keywords: Cooperative hydration; Hydrogen bonding; Hydrophobic interaction; Protein stability; Solution structure; Thermal unfolding; Unfolding enthalpy; Water activity