Study of the interactions between a proline-rich protein and a flavan-3-ol by NMR: residual structures in the natively unfolded protein provides anchorage points for the ligands.
2009
Pascal, Christine | Paté, Franck | Cheynier, Véronique | Delsuc, Marc-André | Sciences Pour l'Oenologie (SPO) ; Université Montpellier 1 (UM1)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro) | Centre de Biochimie Structurale [Montpellier] (CBS) ; Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS) | Institut de génétique et biologie moléculaire et cellulaire (IGBMC) ; Université Louis Pasteur - Strasbourg I-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
International audience
Show more [+] Less [-]English. Astringency is one of the major organoleptic properties of food and beverages that are made from plants, such as tea, chocolate, beer, or red wine. This sensation is thought to be due to interactions between tannins and salivary proline-rich proteins, which are natively unfolded proteins. A human salivary proline-rich protein, namely IB-5, was produced by the recombinant method. Its interactions with a model tannin, epigallocatechin gallate (EGCG), the major flavan-3-ol in green tea, were studied here. Circular dichroism experiments showed that IB-5 presents residual structures (PPII helices) when the ionic strength is close to that in saliva. In the presence of these residual structures, IB-5 undergoes an increase in structural content upon binding to EGCG. NMR data corroborated the presence of preformed structural elements within the protein prior to binding and a partial assignment was proposed, showing partial structuration. TOCSY experiments showed that amino acids that are involved in PPII helices are more likely to interact with EGCG than those in random coil regions, as if they were anchorage points for the ligand. The signal from IB-5 in the DOSY NMR spectrum revealed an increase in polydispersity upon addition of EGCG while the mean hydrodynamic radius remained unchanged. This strongly suggests the formation of IB-5/EGCG aggregates.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by Institut national de la recherche agronomique