Loss of structural integrity and hydrophobic ligand binding capacity of acetylated and succinylated bovine beta-lactoglobulin

Abstract

The lysine residues of bovine beta-lactoglobulin (beta-lg) were acetylated and succinylated to investigate the effect of chemical modification on tertiary and secondary structures. Both derivatives showed higher electrophoretic mobility compared with native beta-lg. The molar extinction coefficients of modified proteins were lower than native beta-lg. A significant decrease in intrinsic trytophan fluorescence intensities, and a red shift of emission maxima were observed. The structural stabilities of the derivatives were compared with the native form. Both modified beta-lg Structures were less stable against guanidine hydrochloride and urea denaturation, Hydrophobicities decreased, as measured by hydrophobic ligand binding of the modified beta-lg. Circular dichroism spectra of modified forms were different. The beta Structural content of modified beta-lactoglobulins decreased substantially with all increase in random coil structure. These modifications changed the tertiary structure. and involved a significant loss of secondary Structure of beta-lg.