Gallic acid oxidizes Met residues in peptides released from bovine β-lactoglobulin by in vitro digestion.
Phenolic compounds (PCs) are frequently present in foods. However, little is known about the effect of PCs on enzymatic digestion process of food proteins and their products. In this study, the effect of gallic acid (GA) on in vitro digestion of β-lactoglobulin (β-LG) was investigated as a model system for analysis of the interaction between PCs and food proteins. GA showed no effect on the initial rate of β-LG digestion. However, after 1.5 h of digestion, the observed degree of hydrolysis of β-LG was lower in the presence than in the absence of GA. The peptides released from β-LG were characterized by LC/IT-TOF-MS and thirty peptides were identified. In particular, four new peaks were obtained following in vitro digestion of β-LG in the presence of GA. Met(7), Met(24) and Met(145) in the peptides corresponding to these peaks were oxidized to methionine sulfoxide residues.
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan.
Ping
P
Lai
Atsushi
A
Okazawa
Yoshihiro
Y
Izumi
Takeshi
T
Bamba
Eiichiro
E
Fukusaki
Masaaki
M
Yoshikawa
Akio
A
Kobayashi
D000818:Animals; D002417:Cattle; D004063:Digestion / Q000187:drug effects; D005707:Gallic Acid / Q000378:metabolism / Q000494:pharmacology*; D006868:Hydrolysis / Q000187:drug effects; D007782:Lactoglobulins / Q000737:chemistry* / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism
D007782:Lactoglobulins; D010446:Peptide Fragments; D005707:Gallic Acid; D008715:Methionine; D014357:Trypsin