Studies on the molecular chaperone abilities of alphaS1- and alphaS2-casein from bovine milk
αs-Casein is a predominant milk protein with important nutritional properties. In addition it has been shown to have molecular chaperone properties similar to those of the sHsps (small heat-shock proteins) and cIusterin. In order to study their relative contributions to the chaperone ability of total αs-casein, the individual subunits, αs1- and αs2-casein, which are present in a ratio of approximately 4:1 (αs1:αs2) in bovine milk were separated and purified from commercially obtained αs-casein. Anion-exchange chromatography was performed in a denaturing and reducing imidazole-Hel buffer at pH 7 as per Thompson et al. (1966) with minor changes, dialyzed against a urea gradient and lyophilized in ammonium acetate buffer.