title: Solubility and stability of cytochrome c in hydrated ionic liquids: effect of oxo acid residues and kosmotropicity.
abstract: Hydrated ionic liquids (ILs) were prepared by adding appropriate amounts of water to hydrophilic ILs. Some hydrated ILs show excellent solubilizing ability for proteins, keeping the basic properties of ILs. The solubility of cytochrome c (cyt c) depended on the structure of the component ions. When component anions have oxo acid residues, the resulting hydrated ILs solubilize cyt c quite well. In such hydrated ILs, the structure and activity of cyt c is influenced by the kosmotropicity of the component ions. We synthesized ILs from various ions having different kosmotropicity, including dihydrogen phosphate (dhp), dibutylphosphate, acetate, lactate, and methanesulfonate as anions. The activity of the dissolved cyt c depends on the permutations of kosmotropicity of the component ions. cyt c shows no structural change and retains its activity when dissolved in the hydrated choline dhp, which is an excellent combination of chaotropic cation and kosmotropic anion. Furthermore, cyt c dissolved in the hydrated choline dhp remained in a native state and was active after 18 months of storage at room temperature.
authors.affiliation: Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Fujita
authors.forename: Douglas R
authors.initials: DR
authors.lastname: MacFarlane
authors.forename: Maria
authors.initials: M
authors.lastname: Forsyth
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshizawa-Fujita
authors.forename: Kenichi
authors.initials: K
authors.lastname: Murata
authors.forename: Nobuhumi
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohno
mesh_terms: D002794:Choline / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry*; D004795:Enzyme Stability; D007477:Ions; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013481:Superoxides / Q000737:chemistry
chemical_list: D007477:Ions; D013481:Superoxides; D045304:Cytochromes c; D002794:Choline