title: Acidic residue modifications restore chaperone activity of β-casein interacting with lysozyme.
abstract: An important factor in medicine and related industries is the use of chaperones to reduce protein aggregation. Here we show that chaperone ability is induced in β-casein by modification of its acidic residues using Woodward's Reagent K (WRK). Lysozyme at pH 7.2 was used as a target protein to study β-casein chaperone activities. The mechanism for chaperone activity of the modified β-casein was determined using UV-vis absorbencies, fluorescence spectroscopy, differential scanning calorimetry and theoretical calculations. Our results indicated that the β-casein destabilizes the lysozyme and increases its aggregation rate. However, WRK-ring sulfonate anion modifications enhanced the hydrophobicity of β-casein resulting in its altered net negative charge upon interactions with lysozyme. The reversible stability of lysozyme increased in the presence of WRK-modified β-casein, and hence its aggregation rate decreased. These results demonstrate the enhanced chaperone activity of modified β-casein and its protective effects on lysozyme refolding.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran. moosavi@ibb.ut.ac.ir
authors.forename: A A
authors.initials: AA
authors.lastname: Moosavi-Movahedi
authors.forename: H
authors.initials: H
authors.lastname: Rajabzadeh
authors.forename: M
authors.initials: M
authors.lastname: Amani
authors.forename: D
authors.initials: D
authors.lastname: Nourouzian
authors.forename: K
authors.initials: K
authors.lastname: Zare
authors.forename: H
authors.initials: H
authors.lastname: Hadi
authors.forename: A
authors.initials: A
authors.lastname: Sharifzadeh
authors.forename: N
authors.initials: N
authors.lastname: Poursasan
authors.forename: F
authors.initials: F
authors.lastname: Ahmad
authors.forename: N
authors.initials: N
authors.lastname: Sheibani
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D002152:Calorimetry, Differential Scanning; D002364:Caseins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002645:Chickens; D004229:Dithiothreitol / Q000494:pharmacology; D007555:Isoxazoles / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D020836:Protein Structure, Quaternary; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: C515594:8-anilino-1-naphthalenesulfonic acid; D000596:Amino Acids; D000817:Anilino Naphthalenesulfonates; D002364:Caseins; D007555:Isoxazoles; D018832:Molecular Chaperones; C009686:N-ethyl-5-phenylisoxazolium-3'-sulfonate; D009113:Muramidase; D004229:Dithiothreitol