STRUCTURE AND DISTRIBUTION OF AGGREGATES FORMED AFTER HEAT-INDUCED DENATURATION OF GLOBULAR-PROTEINS

The structure of aggregates formed upon heat-induced denaturation of beta-lactoglobulin at pH 7.0 and 0.1 RI ammonium acetate is studied by dynamic and static light scattering and small-angle neutron scattering. The internal structure and size distribution of the aggregates is found to be independent of the heating conditions (70 and 76 degrees C) and concentration (0.4, 2.0, 10, 30 g/L). The aggregates are self-similar down to a length scale of about 5 nm with a fractal dimension d(f) = 2.02 +/- 0.02. The experimental results are compatible with a power law aggregation number distribution with an exponential cutoff at a characteristic aggregation number s(*): n(s) proportional to s(-tau) exp(-s/s(*)). From explicit analysis of dynamic light-scattering results the polydispersity coefficient tau is found to be close to unity. The internal dynamics are intermediate between those of fully flexible polymers and rigid aggregates.