Covalent bonding of 4-methylcatechol to β-lactoglobulin results in the release of cysteine-4-methylcatechol adducts after in vitro digestion
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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.
|Status||Udgivet - 2022|
Marianne Nissen Lund reports financial support was provided by Independent Research Fund Denmark. Khadija Waqar reports financial support was provided by Punjab Educational Endowment Fund.
Punjab Educational Endowment Fund (PEEF) is acknowledged for financial support of PhD scholarship to KW, and Independent Research Fund Denmark for funding of grant no. 7017-00133B to MNL.
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