beta-lactoglobulin hydrolysis. 2. Peptide identification, SH/SS exchange, and functional properties of hydrolysate fractions formed by the action of plasmin.
beta-Lactoglobulin (betaLg) was hydrolyzed by plasmin to a degree of hydrolysis of 4%. The hydrolysate was fractionated by ion-exchange chromatography and subsequent hydrophobic-interaction chromatography. The betaLg peptide fraction consisting of smaller peptides (mostly <2 kDa) had poor foam- and emulsion-forming and -stabilizing properties. Most of the betaLg peptides were identified (in either the nonreduced or reduced form) by mass spectrometry on the basis of the known primary structure of the intact protein and the specificity of the enzyme. The peptides formed during betaLg/plasmin-hydrolysis were (1) peptides lacking a cysteyl residue, (2) peptides composed of a single amino acid chain containing intramolecular disulfide bonds, and (3) peptides composed of two amino acid chains linked by an intermolecular disulfide bond. It appeared that significant SH/SS-exchange had taken place during hydrolysis. Many of the peptides present in the peptide fraction that exhibited good functional properties were disulfide-linked fragments.
Caessens
P W
PW
Department of Food Technology and Nutritional Sciences, Wageningen Agricultural University, The Netherlands.
Daamen
W F
WF
Gruppen
H
H
Visser
S
S
Voragen
A G
AG
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000032:analysis; D005341:Fibrinolysin / Q000378:metabolism*; D006868:Hydrolysis; D007782:Lactoglobulins / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004220:Disulfides; D007782:Lactoglobulins; D010446:Peptide Fragments; D005341:Fibrinolysin