title: Relative hydrophobicity between the phases and partition of cytochrome-c in glycine ionic liquids aqueous two-phase systems.
abstract: In this work, glycine ionic liquids tetramethylammonium glycine ([N1111][Gly]), tetraethylammonium glycine ([N2222][Gly]), tetra-n-butylammonium glycine ([N4444][Gly]), tetra-n-butylphosphonium glycine ([P4444][Gly]) and tetra-n-pentylammonium glycine ([N5555][Gly]) were synthesized and used to prepare aqueous two-phase systems (ATPSs) in the presence of K2HPO4. Binodal curves of such ATPSs and partition coefficients of a series of dinitrophenylated (DNP) amino acids in these ATPSs were determined at 298.15K to understand the effect of cationic structure of the ionic liquids on the phase-forming ability of glycine ionic liquids, relative hydrophobicity between the phases in the ionic liquids ATPSs, and polarity of the ionic liquids-rich phases. With the attempt to correlate the relative hydrophobicity of the phases in the ATPSs with their extraction capability for proteins, partition coefficients of cytochrome-c in the ATPSs were also determined. It was shown that partition coefficients of cytochrome-c were in the range from 2.83 to 20.7 under the studied pH conditions. Then, hydrophobic interactions between cytochrome-c and the ionic liquid are suggested to be the main driving force for the preferential partition of cytochrome-c in the glycine ionic liquid-rich phases of the ATPSs. Result derived from polarity of the ionic liquids-rich phases supports this mechanism.
authors.affiliation: School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, China.
authors.forename: Changzeng
authors.initials: C
authors.lastname: Wu
authors.forename: Jianji
authors.initials: J
authors.lastname: Wang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Jing
authors.forename: Huiyong
authors.initials: H
authors.lastname: Wang
mesh_terms: D045304:Cytochromes c / Q000302:isolation & purification*; D005998:Glycine / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D052578:Ionic Liquids; D014867:Water / Q000737:chemistry
chemical_list: D052578:Ionic Liquids; D014867:Water; D045304:Cytochromes c; D005998:Glycine
keywords: Aqueous two-phase systems; Extraction of cytochrome-c; Glycine ionic liquids; Relative hydrophobicity