title: Ionic liquid-induced structural and activity changes in hen egg white lysozyme.
abstract: Lysozyme crystals in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim]BF(4)), 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl), 1-butyl-3-methylimidazolium bromide([C(4)mim]Br), and 1,3-dimethylimidazolium iodine([dmim]I) were prepared, and the influence of ionic liquids (ILs) on the structure and activity change of lysozyme was investigated. Fourier transform infrared spectroscopy revealed the major secondary structures of α-helix and β-sheet for lysozyme. It was interesting to note that increases of the band near 2,935 and 1,656 cm(-1) from Raman spectroscopy are attributed to the unfolding of lysozyme molecules. A shift in amide III from 1,230 to 1,270 cm(-1) in adding [dmim]I occurs, indicating a transformation from β-sheet to random coil. With regard to adding [C(4)mim]BF(4), [C(4)mim]Cl, and [C(4)mim]Br, α-helix and β-sheet are the predominant structures for lysozyme. The activity study showed that the ILs used brought a positive effect. Especially, [dmim]I leads to a drastic increase in relative activity, and its value reaches 50 %.
authors.affiliation: School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Le-Ping
authors.initials: LP
authors.lastname: Dang
authors.forename: Wen-Zhi
authors.initials: WZ
authors.lastname: Fang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Hua-Zhi
authors.initials: HZ
authors.lastname: Xiao
authors.forename: Zhan-Zhong
authors.initials: ZZ
authors.lastname: Wang
mesh_terms: D003460:Crystallization; D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D052578:Ionic Liquids; C421864:hen egg lysozyme; D009113:Muramidase