αs-casein inhibits the pressure-induced aggregation of β-lactoglobulin through its molecular chaperone-like properties

In this work, the effects of as-casein (alpha(s)-CN) on the pressure-induced aggregation of beta-lactoglobulin (beta-Lg) were studied. alpha(s)-CN depressed the pressure-induced aggregation of beta-Lg, and this function was dependent on the concentration of alpha(s)-CN and the pressure holding time. Furthermore, alpha(s)-CN altered the aggregation process of beta-Lg by suppressing the transition of the aggregate from the soluble phase to the insoluble phase and, as a result, the fraction of insoluble aggregates was decreased. During this process, alpha(s)-CN formed stable complexes with the denatured beta-Lg and the formation of complexes prevented further aggregation of beta-Lg and solubilized aggregated beta-Lg to a small degree of polymerization. These results indicate that alpha(s)-CN exhibits a chaperone-like activity under high pressure, and provide an insight into the possible mechanism by which alpha(s)-CN accomplishes the task of stabilizing proteins to resist the pressure-induced aggregation of beta-Lg. (C) 2011 Elsevier Ltd. All rights reserved.