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 (Vitis vinifera 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 (TM) 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.

中文翻译：

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主要葡萄酒蛋白质的二级结构在与多酚相互作用时发生改变

多酚是葡萄酒的重要成分，因其抗氧化特性以及对葡萄酒质量和稳定性的影响而受到广泛研究，这也与其与蛋白质结合的能力有关。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，以及白葡萄酒原花青素总提取物对主要葡萄酒蛋白 VVTL1（Vitis vinifera Thaumatin-Like-1）构象特性的影响）通过同步辐射圆二色性（SRCD）进行研究。结果表明，VVTL1 与多酚相互作用，二级（远紫外）和三级（近紫外）结构的变化证明了这一点，不同多酚对二级结构（远紫外）和三级（近紫外）结构的影响不同。此外，多酚改变了 VVTL1 的两个熔解温度 (TM)（单独蛋白质为 32.2 °C 和 53.9 °C）。近紫外区域的圆二色性 (CD) 光谱揭示了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，从而改变其热和紫外变性模式。这些信息有助于了解葡萄酒蛋白质在多酚存在下的行为，从而为葡萄酒稳定性所涉及的现象提供新的见解。