The Critical Aggregation Concentration of β-Lactoglobulin-Based Fibril Formation

The critical aggregation concentration (CAC) for fibril formation of beta-lactoglobulin (beta-lg) at pH 2 was determined at 343, 353, 358, 363, and 383 K using a Thioflavin T assay and was approximately 0.16 wt%. The accuracy of the CAC was increased by measuring the conversion into fibrils at different stirring speeds. The corresponding binding energy per mol, as determined from the CAC, was 13 RT (similar to 40 kJ mol(-1)) for the measured temperature range. The fact that the CAC was independent of temperature within the experimental error indicates that the fibril formation of beta-lg at pH 2 and the measured temperature range is an entropy-driven process.