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Hydrolysis of β‐lactoglobulin by thermolysin and pepsin under high hydrostatic pressure
Author(s) -
Dufour Eric,
Hervé Guy,
Haertle Tomasz
Publication year - 1995
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360350506
Subject(s) - thermolysin , chemistry , pepsin , hydrolysis , hydrostatic pressure , chromatography , cleavage (geology) , peptide , whey protein , biochemistry , enzyme , trypsin , thermodynamics , physics , geotechnical engineering , fracture (geology) , engineering
Hydrolysis of β‐lactoglobulin with thermolysin and pepsin at pressures ranging between 0.1 and 350 MPa showed a significant increase of cleavage rates. Pressure‐induced changes of susceptibility to hydrolysis of β‐lactoglobulin proteolytic sites were also observed. The pressure, raised to 200 MPa, accelerates the hydrolysis of β‐lactoglobulin by thermolysin and changes obtained peptide profiles. Initially, higher pressure makes the N‐terminal, and to a smaller extent, C‐terminal peptide fragments of β‐lactoglobulin molecule, more susceptible to removal by thermolysin. This indicates combined influence of pressure‐induced thermolysin activation and partial unfolding of β‐lactoglobulin by compression at neutral pHs. The rates of hydrolysis of β‐lactoglobulin by pepsin (negligible at 0.1 MPa) are increased considerably with pressure up to 300 MPa. The Susceptibility of β‐lactoglobulin proteolytic sites to peptic cleavage remains constant over all the studied pressure range. The lack of significant qualitative changes in the peptic peptide profiles produced at different pressures and at clearly pressure‐dependent rates points to negative reaction volume changes as the major factor in peptic hydrolysis of β‐lactoglobulin under high pressure. Thus the β‐lactoglobulin molecule resists pressure‐induced unfolding in acid pHs and yields to it in neutral pHs. © 1995 John Wiley & Sons, Inc.