Interactions between a Non Glycosylated Human Proline-Rich Protein and Flavan-3-ols Are Affected by Protein Concentration and Polyphenol/Protein Ratio

作者：Christine Pascal, Céline Poncet‐Legrand, Anne Imberty, Catherine Gautier, Pascale Sarni‐Manchado, Véronique Cheynier, Aude Vernhet · 发表于：Journal of Agricultural and Food Chemistry · 年份：2007 · DOI：10.1021/jf0704108 · 被引用次数：154 · 研究领域：Metabolomics and Mass Spectrometry Studies、Biochemical effects in animals、Meat and Animal Product Quality

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.