THE EFFECT OF HEAT-TREATMENT ON BOVINE IMMUNOGLOBULINS

The effect of heat on bovine immunoglobulins from colostrum is investi gated both in terms of thermally induced conformational changes, monit ored by differential scanning calorimetry (DSC), and aggregation by me asuring the hydrodynamic radius with photon correlation spectroscopy ( PCS). The DSC measurements show that the unfolding is irreversible and not very dependent on pH. However, the temperature of the transition is lowered upon replacing buffered saline with pure water and if the i nternal disulphide bridges are reduced by beta-mercaptoethanol. The hy drodynamic radius is smaller in phosphate buffered saline solution tha n in water, suggesting that the presence of salt stabilises the immuno globulins against aggregation. At 60-degrees-C, the size of aggregates increase more rapidly with time, when pH closer to the isoelectric po int is chosen.