Multiple interactions between polyphenols and a salivary proline-rich protein repeat result in complexation and precipitation
Multiple interactions between polyphenols and a salivary proline-rich protein repeat result in complexation and precipitation
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DOI：
10.1021/bi9700328
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发表时间：
1997-05-06
期刊：
影响因子：
2.9
通讯作者：
Williamson, MP
中科院分区：
文献类型：
--
作者：
Baxter, NJ;Lilley, TH;Williamson, MP
饮食中的多酚(单宁)不仅沉淀口腔蛋白质，产生收敛的感觉，而且还与饮食蛋白质和肠道中的消化酶相互作用，产生各种抗营养和毒性作用。唾液富含脯氨酸的蛋白(PRPS)分泌到口腔中，与饮食中的多酚形成络合物并沉淀，因此，它们构成了哺乳动物对摄入单宁的主要防御。为了表征这种相互作用，进行了核磁共振研究，包括将一系列多酚滴定为合成的19个残基的PRP片段。结果表明，主要的结合方式是多酚环疏水堆积在Pro-S面上，Pro-Pro序列的第一个Pro残基是一个特别有利的结合部位。解离常数的测定表明，较大和越复杂的多酚与PRP片段相互作用越强；结合亲和力的顺序为原花青素二聚体B-2>；五合金基葡萄糖>；三别基葡萄糖>；>；原花青素单体(-)表儿茶素近似于没食子酸丙酯。较小的多酚可以与堆积在每个Pro残基上的一个酚环结合，而较大的多酚占据两到三个连续的Pro。越复杂的多酚与PRP片段以多齿方式相互作用；而且，当结合时，它们会自结合或堆积。因此，提出了多个多酚/多酚和多酚/PRP相互作用协同作用实现降水的模型。
Polyphenols (tannins) in the diet not only precipitate oral proteins, producing an astringent sensation, but also interact with dietary proteins and digestive enzymes in the gut, resulting in a variety of antinutritive and toxic effects. Salivary proline-rich proteins (PRPs), which are secreted into the oral cavity, form complexes with and precipitate dietary polyphenols, and thus, they constitute the primary mammalian defense directed against ingested tannins. In order to characterize the interaction, NMR studies were performed which involved titrating a series of polyphenols into a synthetic 19-residue PRP fragment. The results show that the predominant mode of association is a hydrophobic stacking of the polyphenol ring against the pro-S face of proline and that the first proline residue of a Pro-Pro sequence is a particularly favored binding site. Measurement of dissociation constants indicates that the larger and more complex polyphenols interact more strongly with the PRP fragment; the order of binding affinity was determined as procyanidin dimer B-2 > pentagalloylglucose > trigalloylglucose >> proanthocyanidin monomer (-)epicatechin approximate to propyl gallate. Smaller polyphenols can bind with one phenolic ring stacked against each proline residue, whereas larger polyphenols occupy two or three consecutive prolines. The more complex polyphenols interact with the PRP fragment in a multidentate fashion; moreover, they self-associate or stack when bound. Thus, a model is proposed in which multiple polyphenol/polyphenol and polyphenol/PRP interactions act cooperatively to achieve precipitation.