β‑Lactoglobulin as a molecular carrier of linoleate: characterization and effects on intestinal epithelial cells in vitro
2012
LE MAUX, SOLENE | Giblin, Linda | Croguennec, Thomas | Bouhallab, Said
The dairy protein β-lactoglobulin (βlg) is known to bind hydrophobic ligands such as fatty acids. In the presentwork, we investigated the biological activity in vitro of linoleate once complexed to bovine βlg. Binding of linoleate (C18:2) tobovine βlg was achieved by heating at 60 °C for 30 min at pH 7.4, resulting in a linoleate/βlg molar binding stoichiometry of 1.1,2.1, and 3.4. Two types of binding sites were determined by ITC titrations. Binding of linoleate induced the formation ofcovalent dimers and trimers of βlg. The LD50 on Caco-2 cells after 24 h was 58 μM linoleate. However, cell viability wasunaffected when 200 μM linoleate was presented to the Caco-2 cells as part of the βlg complex. The Caco-2 cells did not increasemRNA transcript levels of long chain fatty acid transport genes, FATP4 and FABPpm, or increase levels of the cAMP signal, inresponse to the presence of 50 μM linoleate alone or as part of the βlg complex. Therefore, it is proposed that βlg can act as amolecular carrier and alter the bioaccessibility of linoleate/linoleic acid.
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