The Effect of Hoffmeister Salts on the Chaperoning Action of β-Casein in Preventing Aggregation of Reduced β-Lactalbumin

Protein aggregation and precipitation is associated with many debilitating diseases including Alzheimer's, Parkinson's, and light-chain amyloidosis. β-Casein, a member of the casein family, has been demonstrated to exhibit chaperone-like activity to protect protein form aggregation. Hofmeister salts (lyotropice series) are a class of ions which have an effect on the solubility and also the stability of proteins. In this study, using a range of Hofmeister salts (Na2SO4, NaCl and KSCN) altered the rate of aggregation and precipitation of α-lactalbumin. The rate of aggregation of α-lactalbumin increased in the presence of all the added salts. However, Na2SO4 had the greatest effect on the rate of aggregation of α-lactalbumin. β-Casein effectively prevented the aggregation of α-lactalbumin but not as well as in the presence of the salt. Interestingly, in the presence of Na2SO4, β-casein was the poorer chaperone toward aggregation of α-lactalbumin compare to in the presence of NaCl and KSCN. Our result showed that all salts had structural effects on the β-casein which affects its chaperone ability. In summary, structural change and kinetic factors maybe be determinant the poorer chaperone ability of β-casein in the presence of salts.