Dual behavior of sodium dodecyl sulfate as enhancer or suppressor of insulin aggregation and chaperone-like activity of camel αS1-casein

Sodium dodecyl sulfate (SDS) at low concentrations considerably enhanced insulin aggregation and reduced the chaperone-like activity of purified camel αS1-casein (αS1-CN). These observed changes were the result of repulsive electrostatic interactions between both negative charged head groups of SDS and αS1-CN, and the net negative charge of insulin molecules, resulting in the greater exposure of hydrophobic patches of insulin and its enhanced aggregation. In contrast, enhanced hydrophobic interactions were primarily responsible for the conformational changes observed in insulin and αS1-CN at high SDS concentrations, resulting in increased binding of SDS and αS1-CN to insulin and its reduced aggregation.