Peptides are building blocks of heat-induced fibrillar protein aggregates of beta-lactoglobulin formed at pH 2.
The proteinaceous material present in beta-lactoglobulin fibrils formed after heating (20 h at 85 degrees C) at pH 2 was identified during this study. Fibrils were separated from the nonaggregated material, and the fibrils were dissociated using 8 M guanidine chloride and 0.1 M 1,4-dithiothreitol (pH 8). Characterization of the different fractions was performed using thioflavin T fluorescence, high-performance size-exclusion chromatography, reversed-phase HPLC, and mass spectrometry (MALDI-TOF). Beta-lactoglobulin was found to be hydrolyzed into peptides with molecular masses between 2000 and 8000 Da, and the fibrils were composed of a part of these peptides and not intact beta-lactoglobulin. The majority of the peptides (both aggregated and nonaggregated) were a result from cleavage of the peptide bonds before or after aspartic acid residues. Explanations for the presence of certain peptide fragments in the fibrils are the hydrophobicity, low charge, charge distribution, and capacity to form beta-sheets.
Akkermans
Cynthia
C
Food Physics Group, Wageningen University, Post Office Box 8129, 6700 EV Wageningen, The Netherlands.
Venema
Paul
P
van der Goot
Atze Jan
AJ
Gruppen
Harry
H
Bakx
Edwin J
EJ
Boom
Remko M
RM
van der Linden
Erik
E
D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D007782:Lactoglobulins / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D011506:Proteins
D007782:Lactoglobulins; D010446:Peptide Fragments; D011506:Proteins