Enhanced refolding of lysozyme with imidazolium-based room temperature ionic liquids： Effect of hydrophobicity and sulfur residue

• Published in: Science China. Chemistry Vol. 55; no. 8; pp. 1657 - 1662
• Main Authors: Bae, Sang-Woo, Chang, Woo-Jin, Koo, Yoon-Mo, Ha, Sung Ho
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science China Press 01.08.2012; Springer Nature B.V
• Subjects: Buffers; Cations; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Dilution; Hydrophobicity; Ionic liquids; Lysozyme; Proteins; Residues; Room temperature; Sulfur; 咪唑类; 室温离子液体; 渣油; 溶菌酶; 疏水性; 硫酸盐; 稀释复性; 重组蛋白; protein refolding; sulfur; hydrophobicity; lysozyme; dilution refolding; room temperature ionic liquid
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-012-4678-7

The expression of recombinant proteins in microorganism frequently leads to the formation of insoluble aggregates, inclusion bodies （IBs）. Thus, the additional in vitro protein refolding process is required to convert inactive IBs into water-soluble active proteins. This study investigated the effect of sulfur residue and hydrophobicity of imidazolium-based room temperature ionic liquids （RTILs） on the refolding of lysozyme as a model protein in the batch dilution method which is the most commonly used refolding method. When lysozyme was refolded in the refolding buffer containing [BF4]-based RTILs with a systematic variety of alkyl chain on cations varying from two to eight, less hydrophobic imidazolium cations having shorter alkyl chains were effective to facilitate lysozyme refolding. Compared to the conventional refolding buffer, 2 times higher lysozyme re- folding yield was obtained in l-ethyl-3-methylimidazolium tetrafluoroborate （[EMIM][BF4]） containing refolding buffer. The refolding yield of lysozyme was even more increased by 2.5 times when 1-butyl-3-methylimidazolium methylsulfate （[BMIM][MS]） containing sulfur residue on anion was used. The sulfur residue in [BMIM][MS] is supposed to improve the refolding yield of lysozyme which has 4 intrarnolecular disulfide bonds. For dilution-based refolding of lysozyme, the opti- mum concentrations of RTILs in refolding buffer were found to be 1.0 M [EMIM][BF4] and 0.5 M [PMIM][MS], respectively. The optimum temperate for dilution-based refolding of lysozyme with RTILs was 4 ℃.