TY - JOUR
T1 - Covalent bonding of 4-methylcatechol to β-lactoglobulin results in the release of cysteine-4-methylcatechol adducts after in vitro digestion
AU - Waqar, Khadija
AU - Engholm-Keller, Kasper
AU - Joehnke, Marcel S.
AU - Chatterton, Dereck E.W.
AU - Poojary, Mahesha M.
AU - Lund, Marianne N.
N1 - Publisher Copyright:
© 2022 The Authors
PY - 2022
Y1 - 2022
N2 - Protein-polyphenol adducts are formed upon covalent bonding between oxidized polyphenols and proteins. 4-Methylcatechol (4MC) is a polyphenol with origin in coffee and is oxidized to 4-methylbenzoquinone (4MBQ) under conditions used during food processing. The present study characterizes 4MBQ-induced covalent modifications on β-lactoglobulin (β-LG) from bovine milk, (henceforth β-LQ) and the effect on protein digestibility. Significant thiol and amine loss was found in β-LQ compared to β-LG. Site-specific 4MBQ-induced modifications were identified on Cys, Lys, Arg, His and Trp in β-LQ. No significant differences between β-LG and β-LQ on in vitro digestibility were observed by assessment with SDS-PAGE, degree of hydrolysis and LC-MS/MS unmodified peptide intensities. Cys-4MC adduct (1.7 ± 0.1 µmol/g) was released from β-LQ after in vitro digestion. Thus, it is relevant to investigate how released Cys-4MC adducts are absorbed in vivo in future studies.
AB - Protein-polyphenol adducts are formed upon covalent bonding between oxidized polyphenols and proteins. 4-Methylcatechol (4MC) is a polyphenol with origin in coffee and is oxidized to 4-methylbenzoquinone (4MBQ) under conditions used during food processing. The present study characterizes 4MBQ-induced covalent modifications on β-lactoglobulin (β-LG) from bovine milk, (henceforth β-LQ) and the effect on protein digestibility. Significant thiol and amine loss was found in β-LQ compared to β-LG. Site-specific 4MBQ-induced modifications were identified on Cys, Lys, Arg, His and Trp in β-LQ. No significant differences between β-LG and β-LQ on in vitro digestibility were observed by assessment with SDS-PAGE, degree of hydrolysis and LC-MS/MS unmodified peptide intensities. Cys-4MC adduct (1.7 ± 0.1 µmol/g) was released from β-LQ after in vitro digestion. Thus, it is relevant to investigate how released Cys-4MC adducts are absorbed in vivo in future studies.
KW - 4-methylbenzoquinone
KW - Amino acid-polyphenol adducts
KW - Michael addition reaction
KW - Polyphenols
KW - Protein-polyphenol bonding
KW - Whey protein
UR - http://www.scopus.com/inward/record.url?scp=85135148565&partnerID=8YFLogxK
U2 - 10.1016/j.foodchem.2022.133775
DO - 10.1016/j.foodchem.2022.133775
M3 - Journal article
C2 - 35917780
AN - SCOPUS:85135148565
VL - 397
JO - Food Chemistry
JF - Food Chemistry
SN - 0308-8146
M1 - 133775
ER -