title: Hydrolysis of whey protein isolate with Bacillus licheniformis protease: fractionation and identification of aggregating peptides.
abstract: The objective of this work was to identify the dominant aggregating peptides from a whey protein hydrolysate (degree of hydrolysis of 6.8%) obtained with Bacillus licheniformis protease. The aggregating peptides were fractionated with preparative reversed-phase chromatography and identified with liquid chromatography-mass spectrometry. The results showed that the dominant aggregating peptide, at pH 7.0, was beta-lg AB [f1-45]. In addition, the peptides beta-lg AB [f90-108]-S-S-alpha-la [f50-113], alpha-la [f12-49]-S-S-alpha-la [f50-113], beta-lg AB [f90-108]-S-S-beta-lg AB [f90-108], beta-lg A [f90-157], and beta-lg AB [f135-157/158] were also identified as main aggregating peptides. The results further showed that aggregation, via hydrophobic interactions, prevented further digestion (at pH 8.0), thereby explaining the large size of the aggregating peptides. It is hypothesized that B. licheniformis protease breaks down hydrophilic segments in the substrate and, therefore, preserves hydrophobic segments that aggregate once exposed to the solvent.
authors: Laboratory of Food Chemistry, Wageningen University, The Netherlands.
authors: Nathalie
authors: N
authors: Creusot
authors: Harry
authors: H
authors: Gruppen
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D005591:Chemical Fractionation; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D007768:Lactalbumin / Q000737:chemistry; D007782:Lactoglobulins / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry; D010447:Peptide Hydrolases / Q000378:metabolism*; D000067816:Whey Proteins
chemical_list: D007782:Lactoglobulins; D008894:Milk Proteins; D010446:Peptide Fragments; D000067816:Whey Proteins; D007768:Lactalbumin; D010447:Peptide Hydrolases