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

Journal of Neurology

Volume 4 - Number

Article Type: ---- Unspecified ----

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 beta-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 beta-casein chaperone activities. The mechanism for chaperone activity of the modified beta-casein was determined using UV-vis absorbencies, fluorescence spectroscopy, differential scanning calorimetry and theoretical calculations. Our results indicated that the beta-casein destabilizes the lysozyme and increases its aggregation rate. However, WRK-ring sulfonate anion modifications enhanced the hydrophobicity of beta-casein resulting in its altered net negative charge upon interactions with lysozyme. The reversible stability of lysozyme increased in the presence of WRK-modified beta-casein, and hence its aggregation rate decreased. These results demonstrate the enhanced chaperone activity of modified beta-casein and its protective effects on lysozyme refolding. (C) 2011 Elsevier B.V. All rights reserved.