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EnglishTannins are a heterogeneous class of polyphenols that are present in several plants and foods. Their ability to interact and precipitate proline-rich proteins leads to different effects such as astringency or antidiarrheal activity. Thus, evaluation of the tannin content in plant extracts plays a key role in understanding their potential use as pharmaceuticals and nutraceuticals. Several methods have been proposed to study tannin-protein interactions but few of them are focused on quantification. The purpose of the present work is to set up a suitable and time efficient method able to quantify the extent of tannin protein precipitation. Bradykinin, chosen as a model, was incubated with increasing concentrations of 1,2,3,4,6-penta-O-galloyl-β-D-glucose and tannic acid selected as reference of tannic compounds. Bradykinin not precipitated was determined by a mass spectrometer TSQ Quantum Ultra Triple Quadrupole (direct infusion analysis). The results were expressed as PC 50 , which is the concentration able to precipitate 50% of the protein. The type of tannin-protein interaction was evaluated also after precipitate solubilisation. The involvement of proline residues in tannin-protein interactions was confirmed by repeating the experiment using a synthesized peptide (RR-9) characterized by the same bradykinin sequence, but having proline residues replaced by glycine residues: no interaction occurred between the peptide and the tannins. Moreover, modelling studies on PGG-BK and PGG-RR-9 were performed to deeply investigate the involvement of prolines: a balance of hydrophobic and H-bond contacts stabilizes the PGG-BK cluster and the proline residues exert a crucial role thus allowing the PGG molecules to elicit a sticking effect.
| Titolo: | Development of a direct ESI-MS method for measuring the tannin precipitation effect of proline-rich peptides and in silico studies on the proline role in tannin-protein interactions |
| Autori: | BARON, GIOVANNA (Primo) ALTOMARE, ALESSANDRA ANNA (Secondo) ALDINI, GIANCARLO (Ultimo) (Corresponding) |
| Parole Chiave: | Mass spectrometry; Proline-rich proteins; Tannins; Bradykinin; Mass Spectrometry; Peptides; Proline; Tannins |
| Settore Scientifico Disciplinare: | Settore CHIM/08 - Chimica Farmaceutica |
| Data di pubblicazione: | lug-2019 |
| Rivista: | |
| Tipologia: | Article (author) |
| Digital Object Identifier (DOI): | 10.1016/j.fitote.2019.05.002 |
| Appare nelle tipologie: | 01 - Articolo su periodico |
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