title: The colloidal state of tannins impacts the nature of their interaction with proteins: the case of salivary proline-rich protein/procyanidins binding.
abstract: While the definition of tannins has been historically associated with its propensity to bind proteins in a nonspecific way, it is now admitted that specific interaction also occurs. The case of the astringency perception is a good example to illustrate this phenomenon: astringency is commonly described as a tactile sensation induced by the precipitation of a complex composed of proline-rich proteins present in the human saliva and tannins present in beverages such as tea or red wines. In the present work, the interactions between a human saliva protein segment and three different procyanidins (B1, B3, and C2) were investigated at the atomic level by NMR and molecular dynamics. The data provided evidence for (i) an increase in affinity compared to shortest human saliva peptides, which is accounted for by protein "wraping around" the tannin, (ii) a specificity in the interaction below tannin critical micelle concentration (CMC) of ca. 10 mM, with an affinity scale such that C2 > B1 > B3, and (iii) a nonspecific binding above tannin CMC that conducts irremediably to the precipitation of the tannins/protein complex. Such physicochemical findings describe in accurate terms saliva protein-tannin interactions and provide support for a more subtle description by oenologists of wine astringency perception in the mouth.
authors.affiliation: Univ. Bordeaux and CNRS, Institut des Sciences Moléculaires, UMR 5255, CESAMO, 351 cours de la Libération, Talence F-33405, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Cala
authors.forename: Erick J
authors.initials: EJ
authors.lastname: Dufourc
authors.forename: Eric
authors.initials: E
authors.lastname: Fouquet
authors.forename: Claude
authors.initials: C
authors.lastname: Manigand
authors.forename: Michel
authors.initials: M
authors.lastname: Laguerre
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pianet
mesh_terms: D044946:Biflavonoids / Q000737:chemistry* / Q000378:metabolism; D002392:Catechin / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008823:Micelles; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D044945:Proanthocyanidins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D055273:Salivary Proline-Rich Proteins / Q000737:chemistry* / Q000378:metabolism; D013634:Tannins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D044946:Biflavonoids; D008823:Micelles; D044945:Proanthocyanidins; D055273:Salivary Proline-Rich Proteins; D013634:Tannins; C017674:procyanidin; D002392:Catechin