Ionic Liquid-Induced Structural and Activity Changes in Hen Egg White Lysozyme

• Published in: Applied biochemistry and biotechnology 2013, Vol.169 (1), p.290-300
• Main Authors: Dang, Le-Ping, Fang, Wen-Zhi, Li, Yan, Wang, Qian, Xiao, Hua-Zhi, Wang, Zhan-Zhong
• Format: Article
• Language: English
• Subjects: Bacteriology; Biochemistry; Biological and medical sciences; Biotechnology; Chemistry; Chemistry and Materials Science; Crystallization; Crystallography; Crystals; Eggs; Enzymes; Fourier transforms; Fundamental and applied biological sciences. Psychology; Infrared spectroscopy; Iodine; Ionic Liquids - chemistry; Kinetics; Muramidase - chemistry; Muramidase - metabolism; Protein Structure, Secondary; Spectroscopy, Fourier Transform Infrared
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-012-9986-z

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 %.