Interactions between Bovine β-Lactoglobulin and Peptides under Different Physicochemical Conditions

Abstract

The aim of this study was to determine if peptides could interact with beta-lactoglobulin (beta-LG) and what the physicochemical conditions promoting their interaction with the protein are. The binding of negatively charged (beta-LG 125-135 and 130-135), positively charged (beta-LG 69-83 and 146-149), and hydrophobic (alphaS1-CN 23-34 and beta-LG 102-105, both bioactive peptides) peptides to bovine beta-LG was determined using an ultrafiltration method under different physicochemical conditions: pH 3.0, 6.8, and 8.0; buffers of 0.05 and 0.1 M; 4, 25, and 40 degrees C; beta-LG/peptide ratios of 1:5 and 1:10. At pH 3.0, none of the peptides interacted with beta-LG at any temperature, buffer molarity, or beta-LG/peptide ratio probably due to electrostatic repulsions between the highly protonated species. At pH 6.8 and 8.0, charged peptides beta-LG 130-135, 69-83, and 146-149 bound to beta-LG under some physicochemical conditions, possibly by nonspecific binding. However, both hydrophobic peptides probably bind to the inner cavity (beta-barrel) of beta-LG, provoking the release of materials absorbing at 214 nm. Given the known biological activities of the hydrophobic peptides used in this study (opioid and ACE-inhibitory activities), their binding to beta-LG may be relevant to a better understanding of the physiological function of the protein.

Physiological, chemical and technological aspects of milk-protein-derived peptides with antihypertensive and ACE-inhibitory activity

“…Interactions between intact milk proteins (i.e. b-Lg) and milk protein-derived peptides have been studied by Noiseux, Gauthier, & Turgeon (2002). At pH 3.0, no peptide/b-Lg interactions were found, possibly because electrostatic repulsion prevented interaction between the positively charged b-Lg and the peptides studied.…”

Peptide–peptide and protein–peptide interactions in mixtures of whey protein isolate and whey protein isolate hydrolysates

“…This information could help understanding of the gelation mechanism in protein hydrolysates. In addition, previous studies have shown the ability of b-lg to interact with peptides (Barbeau, Gauthier, & Pouliot, 1996;Noiseux, Gauthier, & Turgeon, 2002).…”

β-Lactoglobulin's Conformational Requirements for Ligand Binding at the Calyx and the Dimer Interphase: a Flexible Docking Study

“…Each BLG monomer consists of 162 residues (18.3 kDa) folded into eight stranded antiparallel β-sheets that form a hydrophobic pocket or calyx, flanked on one side by an α-helix [8] (Figure 1A and B). Although its biological function is uncertain [9], BLG is relevant to the food and pharmaceutical industries due to its ability to bind fatty acids, vitamins and peptides and it has been the subject of numerous biochemical and structural studies. For hydrophobic ligands two sites have been postulated: one inside the calyx (referred here to as Site A) and the other at the dimer interface, on the outer surface of the protein between the α-helix and the β-barrel (hereby referred to as Site B) [5,10].…”