Effect of salts and sodium dodecyl sulfate on chaperone activity of camel αS1-CN: Insulin as the target protein

In this study camel αS1-casein (αS1-CN) was purified, using a two-step purification procedure. The anti-aggregation (chaperone-like) ability of the purified protein sample was examined in a wide range of experimental conditions and at different concentrations of camel αS1-CN, in the presence of salts and sodium dodecyl sulfate (SDS). To examine chaperone-like activity of camel αS1-CN, bovine pancreatic insulin was used as the target protein. Insulin aggregation performed chemically in the presence of 20 mM dithiotreitol (DTT) and was studied at 360 nm wavelength by UV–vis spectrophotometer. Camel αS1-CN exhibited a dose-dependent chaperone-like activity as the molar ratios of chaperone/target protein varied between 0 and 0.07. The presence of salts or surfactants changing the protein properties had an influence on chaperone capacity of camel αS1-CN. The results of UV–visible and fluorimetric measurements indicated that the salts neutralize the chaperone-like activity of casein due to dehydration effect and the increased association and aggregation of proteins, while SDS plays a role as chaperone and chaperone-like properties of camel αS1-CN enhanced in the presence of SDS due to the binding of the hydrophobic tail of SDS and αS1-CN to the exposed hydrophobic sites of insulin strongly preventing aggregation of insulin.