Thermodynamic studies of the effect of temperature (27-47 ºC) on the structure of bovine b-lactoglobulin-A (BLG-A) in the absence and presence of Cr(III) containing 50 mmol L-1 sodium chloride have been carried out using UV-Visible absorption spectroscopy, far and near circular dichroism (CD) and fluorescence spectroscopy. The far-UV CD studies do not show any significant change in the secondary structure of the protein at different temperatures in the absence and presence of Cr(III). On the contrary, the near-UV CD studies show change in the tertiary structure of the native BLG on increasing the temperature, indicating the exposure of Tyr residues. Fluorescence spectroscopic studies on the native BLG-A in the absence and presence of Cr(III) represent considerable change in the tertiary structure of the protein due to the increase in temperature. Due to protein stabilization in the presence of Cr(III) ions, the tertiary structure of BLG represents considerable alterations at 37 and 47 ο C that is in agreement with increasing of Tm values at these temperatures.
β-lactoglobulin; temperature; Cr(III) ions; tertiary structure; Tm value
