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Impact of Proline-Rich Salivary Proteins on Interactions between Catechin and Polysaccharides
Philippe Rodrigues Benedetti1, Leociley Rocha Alencar Menezes1, Guilherme Lanzi Sassaki1
1Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, Paraná81.531-980, Brazil.
Abstract:
The modulation of interactions between catechin and two structurally distinct wine polysaccharides (mannan and pectin) by proline-rich salivary proteins (PRPs) was investigated using saturation transfer difference nuclear magnetic resonance (STD NMR). Mannan-catechin interactions, driven by CH-π stacking and hydrophobic effects, were weakened by both acidic and basic PRPs. This competitive interference increased the apparent dissociation constant (KD) from ≈231 μM to ≈272 and 279 μM, respectively. Conversely, catechin-pectin binding (baseline KD ≈ 230 μM) was unaffected by acidic PRPs but synergistically enhanced by basic PRPs (KD ≈ 195 μM) due to favorable electrostatic attractions. Epitope mapping confirmed that catechin binds differently depending on the polysaccharide structure. Ultimately, the results reveal a dual regulatory pattern: PRPs act as competitive antagonists for neutral polysaccharides (mannan) and cooperative synergists for charged ones (pectin). These molecular insights provide a concrete biophysical basis for strategically managing wine astringency and sensory quality.
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