Heat-induced aggregation of beta-lactoglobulin AB at pH 2.5 as influenced by ionic strength and protein concentration

Heat-induced (80 degrees C) aggregation of beta-lactoglobulin AB at pH 2.5 was studied using size-exclusion chromatography in combination with multi-a ngle laser light scattering, dynamic light scattering and electrophoretic t echniques. Upon heating, large aggregates with molar masses of 10(6)-10(7) Da were formed, whereas the concentration of intermediate-sized aggregates was very low. The rate of disappearance of native-like beta-lactoglobulin i ncreased with increasing protein concentration (reaction order 2) and ionic strength. Aggregate size increased slightly with heating time and ionic st rength, but was independent of protein concentration. Aggregates were held together entirely with non-covalent bonding. (C) 2000 Elsevier Science Ltd. All rights reserved.