Proteolytic Pattern, Antigenicity, and Serum Immunoglobulin E Binding of β-Lactoglobulin Hydrolysates Obtained by Pepsin and High-Pressure Treatments

The SDS-PAGE of hydrolysates of β-LG obtained with pepsin under different pressure conditions. Lane 1: control native β-LG; lanes 2 and 3: hydrolysates obtained at atmospheric pressure on native β-LG for 8 and 24h, respectively. Lanes 4, 5, 6, and 7: hydrolysates obtained at atmospheric pressure for 1h on prepressurized β-LG (100, 200, 300, and 400MPa, respectively, for 20min); lanes 8, 9, 10, and 11: hydrolysates obtained under high pressure, at 100, 200, 300, and 400MPa, respectively, for 20min on native β-LG.

HPLC-UV chromatograms of β-LG hydrolysates obtained with pepsin in the absence (a, c, e) and presence of dithiothreitol (DTT; b, d, f). Native β-LG hydrolyzed at atmospheric pressure for 48h (a, b); prepressurized β-LG (400MPa, 20min) hydrolyzed at atmospheric pressure for 60min (c, d); native β-LG hydrolyzed under 400MPa for 5min (e, f). Peak numbers correspond to the peptides identified by MS/MS (Table 2). F1, F2, F3, and F4 correspond to the fractions in Table 1.

View of the 3D structure of β-LG and some primary fragments favorably cleaved by proteolysis with pepsin under high pressure. Model built with RasWin Molecular Graphics, version 2.6, using the coordinates from the Protein Data Bank, PDB ID: 1BEB (Brownlow et al., 1997).