title: Interactions between a non glycosylated human proline-rich protein and flavan-3-ols are affected by protein concentration and polyphenol/protein ratio.
abstract: Interactions between salivary proline-rich proteins and tannins are involved in astringency, which is one of the most important organoleptic sensations perceived when drinking wine or tea. This work aimed to study interactions between a recombinant human salivary proline-rich protein, IB-5, and a flavan-3-ol monomer, epigallocatechin gallate (EGCG). IB-5 presented the characteristics of natively unfolded proteins. Interactions were studied by dynamic light scattering, isothermal titration microcalorimetry, and circular dichroism. The interaction mechanism was dependent on protein concentration. At low concentrations, a three-stage mechanism was evidenced. Saturation of the interaction sites (first stage) was followed by protein aggregation into metastable colloids at higher EGCG/protein ratios (second stage). Further increasing this ratio led to haze formation (third stage). At low ratios, a disorder-to-order transition of IB-5 structure upon binding was evidenced. At high protein concentrations, direct bridging between proteins and EGCG was observed, resulting in significantly lower aggregation and turbidity thresholds.
authors.affiliation: UMR INRA-Montpellier SupAgro 1083 Sciences Pour l'Oenologie, 2 place Pierre Viala, F-34060 Montpellier, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Pascal
authors.forename: Céline
authors.initials: C
authors.lastname: Poncet-Legrand
authors.forename: Anne
authors.initials: A
authors.lastname: Imberty
authors.forename: Catherine
authors.initials: C
authors.lastname: Gautier
authors.forename: Pascale
authors.initials: P
authors.lastname: Sarni-Manchado
authors.forename: Véronique
authors.initials: V
authors.lastname: Cheynier
authors.forename: Aude
authors.initials: A
authors.lastname: Vernhet
mesh_terms: D000595:Amino Acid Sequence; D002392:Catechin / Q000031:analogs & derivatives / Q000378:metabolism; D005419:Flavonoids / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000378:metabolism*; D010636:Phenols / Q000378:metabolism; D059808:Polyphenols; D055232:Proline-Rich Protein Domains; D012471:Salivary Proteins and Peptides / Q000378:metabolism
chemical_list: D005419:Flavonoids; D010446:Peptide Fragments; D010455:Peptides; D010636:Phenols; D059808:Polyphenols; D012471:Salivary Proteins and Peptides; C404987:flavan-3-ol; D002392:Catechin; C045651:epigallocatechin gallate