Acidic residue modifications restore chaperone activity of β-casein interacting with lysozyme.

PubMed ID: 21802443

Author(s): Moosavi-Movahedi AA, Rajabzadeh H, Amani M, Nourouzian D, Zare K, Hadi H, Sharifzadeh A, Poursasan N, Ahmad F, Sheibani N. Acidic residue modifications restore chaperone activity of β-casein interacting with lysozyme. Int J Biol Macromol. 2011 Nov 1;49(4):616-21. doi: 10.1016/j.ijbiomac.2011.06.020. Epub 2011 Jul 22. PMID 21802443

Journal: International Journal Of Biological Macromolecules, Volume 49, Issue 4, Nov 2011

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.