Formation of new protein structures in heated mixtures of BSA and alpha-lactalbumin.
The heat-induced protein-protein interactions of alpha-lactalbumin (alpha-La) and bovine serum albumin (BSA), dispersed in a pH 6.8, 10% whey protein concentrates (WPC) permeate, were followed using alkaline and sodium dodecyl sulfate (SDS) 1D and 2D polyacrylamide gel electrophoresis (PAGE) and size-exclusion high-performance liquid chromatography (SE-HPLC). Heated (75 degrees C) 5% BSA solution contained large disulfide-bonded BSA aggregates, although some monomer BSA (SDS-monomeric BSA) could be dissociated from the aggregates by SDS. In contrast, similarly heated alpha-La solutions contained small quantities of several monomeric forms of alpha-La and dimeric alpha-La but no large aggregates. When 10% solutions of 1:1 (w/w) mixtures of alpha-La and BSA were heated, large disulfide-bonded aggregates and SDS-monomeric BSA and alpha-La were present. However, heated 2% mixtures contained more modified alpha-La monomers, alpha-La-dimers, and alpha-La-trimers, fewer large disulfide-bonded aggregates, and less SDS-monomeric alpha-La or BSA. These results suggest that BSA forms disulfide-bonded aggregates that contain available thiol groups that can catalyze the formation of differently structured alpha-La monomers, dimers, higher polymers, and adducts of alpha-La with BSA.
Havea
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Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
Singh
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Creamer
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LK
D000818:Animals; D001704:Biopolymers; D002417:Cattle; D006358:Hot Temperature; D007768:Lactalbumin / Q000737:chemistry*; D011487:Protein Conformation; D012710:Serum Albumin, Bovine / Q000737:chemistry*
D001704:Biopolymers; D012710:Serum Albumin, Bovine; D007768:Lactalbumin