AGGREGATION OF BOVINE BETA-LACTOGLOBULIN-A AND BETA-LACTOGLOBULIN-B ON HEATING AT 75-DEGREES-C

The aggregation of beta-lactoglobulin (beta-lg) genetic variants A and B, isolated from milks of individual cows that were homozygous for ea ch variant, and dissolved in imidazole-HCl buffer containing 0.1 mol L (-1) NaCl, was examined using high performance liquid chromatography o n a TSK-GEL G4000SW column. The extent of aggregation after heating at 75 degrees C increased with heating time and protein concentration, a nd there were marked differences between the aggregation behaviour of the two variants. Below a protein concentration of 5% (w/v), the aggre gation was faster for the B than for the A variant but above 5% (w/v), the A variant appeared to be more sensitive to thermal aggregation. T he conflicting results reported in the literature on the thermal denat uration of beta-lg A and B could be explained on the basis of differen t protein concentrations used by different researchers. (C) 1996 Elsev ier Science Limited