Perez-Gregorio M R, Mateus N, de Freitas V
Departamento de Quimica e Bioquimica, Faculdade de Ciências da Universidade do Porto , Rua Campo Alegre 687, 4169-007 Porto, Portugal.
Langmuir. 2014 Jul 22;30(28):8528-37. doi: 10.1021/la502184f. Epub 2014 Jul 14.
Astringency is mainly attributed to the interaction between tannins and salivary proteins. Proline-rich proteins, histatins, and statherins are supposed to be the most reactive salivary proteins. This study aims to contribute to the knowledge of the tannin-protein binding process in saliva. It was identified for the first time in several soluble tannin-human salivary protein aggregates. A rapid mass spectrometry analytical method (MALDI-TOF and FIA-ESI-MS) was developed to identify new soluble tannin-human salivary protein aggregates. Three different tannins--procyanidin B3 (B3), procyanidin B2 gallate (B2G), and pentagalloylglucoside (PGG)--were tested to elucidate the tannin selectivity toward histatins, proline-rich proteins, and statherins in human saliva. A greater number of aggregates with a higher molecular weight was found when PGG was tested while no difference in the number and molecular mass range was observed in B3 or B2G salivary protein aggregates. This study confirms for the first time the bilateral selectivity of tannins and protein to yield soluble tannin-human salivary protein complexes. The results confirm that B3 and B2G are more selective than PGG. Furthermore, the families of proteins involved in the majority of B3-salivary protein soluble aggregates were primarly histatins, followed by basic proline-rich proteins and statherins. When B2G was tested, basic proline-rich proteins were involved in a greater number of aggregates, followed by histatines and statherins. Basic proline-rich proteins were also the family of proteins that formed a greater number of PGG-salivary protein aggregates followed by statherins and histatins. Acidic proline-rich proteins and glucosilated proline-rich proteins formed fewer soluble aggregates regardless of the tannin tested. The aggregation process was also found to be influenced by tannin and protein polarity. Indeed, the protein/tannin ratio of soluble aggregates increased with the tannin polarity. On the other hand, the only amphiphilic salivary proteins studied (histatins) formed a greater number of aggregates with the least polar tannin tested (B3).
涩味主要归因于单宁与唾液蛋白之间的相互作用。富含脯氨酸的蛋白、组蛋白和富组蛋白被认为是最具反应性的唾液蛋白。本研究旨在增进对唾液中单宁 - 蛋白质结合过程的了解。在几种可溶性单宁 - 人唾液蛋白聚集体中首次鉴定出相关物质。开发了一种快速质谱分析方法（基质辅助激光解吸电离飞行时间质谱和流动注射电喷雾电离质谱）来鉴定新的可溶性单宁 - 人唾液蛋白聚集体。测试了三种不同的单宁——原花青素B3（B3）、原花青素B2没食子酸酯（B2G）和五倍子酰葡萄糖（PGG）——以阐明单宁对人唾液中组蛋白、富含脯氨酸的蛋白和富组蛋白的选择性。测试PGG时发现了更多分子量更高的聚集体，而在B3或B2G唾液蛋白聚集体中未观察到数量和分子量范围的差异。本研究首次证实了单宁和蛋白质产生可溶性单宁 - 人唾液蛋白复合物的双向选择性。结果证实B3和B2G比PGG更具选择性。此外，参与大多数B3 - 唾液蛋白可溶性聚集体的蛋白质家族主要是组蛋白，其次是碱性富含脯氨酸的蛋白和富组蛋白。测试B2G时，碱性富含脯氨酸的蛋白参与的聚集体数量更多，其次是组蛋白和富组蛋白。碱性富含脯氨酸的蛋白也是形成PGG - 唾液蛋白聚集体数量较多的蛋白质家族，其次是富组蛋白和组蛋白。无论测试何种单宁，酸性富含脯氨酸的蛋白和糖基化富含脯氨酸的蛋白形成的可溶性聚集体较少。还发现聚集过程受单宁和蛋白质极性的影响。实际上，可溶性聚集体的蛋白质/单宁比值随单宁极性增加而增加。另一方面，所研究的唯一两亲性唾液蛋白（组蛋白）与测试的极性最小的单宁（B3）形成的聚集体数量更多。
