Identification of Peptides in Aggregates Formed during Hydrolysis of β-Lactoglobulin B with a Glu and Asp Specific Microbial Protease

• Published in: Journal of agricultural and food chemistry Vol. 48; no. 6; pp. 2443 - 2447
• Main Authors: Otte, J, Lomholt, S. B, Halkier, T, Qvist, K. B
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.06.2000
• Subjects: Amino Acid Sequence; Aspartic Acid; Bacillus - enzymology; Biological and medical sciences; Endopeptidases - metabolism; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Glutamic Acid; Hydrolysis; Lactoglobulins - chemistry; Methods of analysis, processing and quality control, regulation, standards; Molecular Sequence Data; Peptide Fragments - chemistry; Protein Folding; Protein Structure, Secondary; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; Peptides; Enzyme; Capillary electrophoresis; Gelation; Hydrophobic interaction; Identification; Protein; Hydrolysis; Peptidases; Analysis method; Enzymatic activity; Lactoglobulins; Aminoacid; pH; Hydrolases; Microorganism; Aggregate; Mass spectrometry; Physicochemical properties; Aminoacid sequence
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf990947o

The purpose of the present study was to identify the peptides responsible for aggregate formation during hydrolysis of β-lactoglobulin by BLP at neutral pH. Hydrolysates taken at various stages of aggregate formation were separated into a precipitate and a soluble phase and each was analyzed by CE and mass spectrometry. The aggregates consisted of six to seven major peptides of which four were tentatively identified. The peptides were positively charged at neutral pH and had a high charge-to-mass ratio at low pH. The fragment f135−158 seemed to be the initiator of aggregation, since it was present at high concentration in the aggregates at all stages, and the concentration of this peptide remained low in the supernatant. F135−158 contains several basic and acid amino acids alternating with hydrophobic amino acids, which is in accordance with formation of noncovalently linked aggregates, as previously shown. Keywords: β-lactoglobulin B; enzymatic hydrolysis; aggregation; peptides; identification