| A method for the purification of α-lactalbumin from whey protein isolate solutions using a hexapeptide ligand has been developed. The peptide WHWRKR was isolated from a peptide library generated by combinatorial chemistry. This peptide displayed affinity to α-lactalbumin. Other proteins from whey protein isolate bound nonspecifically to the resin used.; Different strategies for production of α-lactalbumin from whey protein isolate using bioselective adsorption are reported. The use of a peptide ligand (WHWRKR) attached to a resin allowed production of an α-lactalbumin-rich fraction with a purity of 90.6% and a recovery of 47.9%, while also producing other fractions of commercial interest. The combined use of an amino resin followed by the WHWRKR resin produced a highly purified α-lactalbumin (100%) with a yield of 35.2%.; An investigation on the mechanism of binding of α-lactalbumin to the peptide ligand WHWRKR and its variants HWRKR and acetylated WHWRKR immobilized on a polymethacrylate chromatographic resin was carried out. The presence of two temperature-dependent binding mechanisms and one temperature-independent mechanism was demonstrated. Injections of different forms of α-lactalbumin (apo-α-lactalbumin, D87A mutant α-lactalbumin, and peptides 1–40/104–123 and 53–103) displayed similar behaviors when compared to native α-lactalbumin, while lysozyme showed little or no binding to the WHWRKR and AcWHWRKR resins. An alternative process for isolation of α-lactalbumin from WPI was developed, using consecutive injections of WPI with limited elution.; Finally, the use of the peptide resin AcWHWRKR in batch mode with sweet whey was tested, demonstrating that although the resin does bind α-lactalbumin properly, an efficient separation does not occur, due to the presence of glycomacropeptide in the elution fraction. |
