Department of Land, Environment, Agriculture and Forestry (TESAF), University of Padua, Viale dell'Università, 16, 35020 Legnaro (PD), Italy.
Institute of Biomolecular Chemistry of CNR, Padua Unit, via Marzolo 1, 35131 Padua, Italy.
Molecules. 2020 Apr 3;25(7):1646. doi: 10.3390/molecules25071646.
Polyphenols are an important constituent of wines and they are largely studied due to their antioxidant properties and for their effects on wine quality and stability, which is also related to their capacity to bind to proteins. The effects of some selected polyphenols, including procyanidins B1 and B2, tannic acid, quercetin, and rutin, as well as those of a total white wine procyanidin extract on the conformational properties of the major wine protein VVTL1 ( Thaumatin-Like-1) were investigated by Synchrotron Radiation Circular Dichroism (SRCD). Results showed that VVTL1 interacts with polyphenols as demonstrated by the changes in the secondary (far-UV) and tertiary (near-UV) structures, which were differently affected by different polyphenols. Additionally, polyphenols modified the two melting temperatures (T) that were found for VVTL1 (32.2 °C and 53.9 °C for the protein alone). The circular dichroism (CD) spectra in the near-UV region revealed an involvement of the aromatic side-chains of the protein in the interaction with phenolics. The data demonstrate the existence of an interaction between polyphenols and VVTL1, which results in modification of its thermal and UV denaturation pattern. This information can be useful in understanding the behavior of wine proteins in presence of polyphenols, thus giving new insights on the phenomena that are involved in wine stability.
多酚是葡萄酒的重要成分，由于其抗氧化特性以及对葡萄酒质量和稳定性的影响（这也与其与蛋白质结合的能力有关），因此它们受到了广泛的研究。通过同步辐射圆二色性（SRCD）研究了一些选定的多酚，包括原花青素 B1 和 B2、单宁酸、槲皮素和芦丁，以及一种总白葡萄酒原花青素提取物对主要葡萄酒蛋白 VVTL1（Thaumatin-Like-1）构象特性的影响。结果表明，VVTL1 与多酚相互作用，如二级（远紫外）和三级（近紫外）结构的变化所证明的那样，不同的多酚对其产生不同的影响。此外，多酚还改变了 VVTL1 的两个熔融温度（T）（单独的蛋白质为 32.2°C 和 53.9°C）。近紫外区的圆二色性（CD）光谱表明，蛋白质的芳香侧链参与了与酚类的相互作用。数据表明多酚和 VVTL1 之间存在相互作用，这导致其热变性和 UV 变性模式发生变化。这些信息有助于理解多酚存在下葡萄酒蛋白的行为，从而深入了解与葡萄酒稳定性相关的现象。
