Food Process Engineering, Wageningen University, 6708WG, Wageningen, The Netherlands.
Biobased Chemistry and Technology, Wageningen University, 6708WG, Wageningen, The Netherlands.
Chemphyschem. 2018 Feb 19;19(4):459-468. doi: 10.1002/cphc.201701054. Epub 2018 Jan 24.
Proteins and phenols coexist in the confined space of plant cells leading to reactions between them, which result in new covalently bonded complex molecules. This kind of reactions has been widely observed during storage and processing of plant materials. However, the nature of the new complex molecules and their physicochemical properties are largely unknown. Therefore, we investigated the structural characteristics of covalently bonded complexes between sunflower protein isolate (SFPI, protein content 85 wt %) and the dominant phenol in the confined space of a sunflower seed cell (chlorogenic acid, CGA). It was shown that the efficiency of bond formation goes through a maximum as a function of the SFPI:CGA ratio. Moreover, the bonding of CGA with proteins resulted in changes in the secondary and tertiary structure of the protein. It was also shown that the phenol bound strongly to the protein, which resulted in new crosslinks between the polypeptide chains. As a result, secondary structures like α-helices and β-sheets diminished, which in turn resulted in more disordered domains and a subsequent modification of the tertiary structure of the proteins. These findings are relevant for establishing future protocols for extraction of high-quality proteins and phenols when utilizing plant material and offer insight into the impact of processing that these ingredients endure.
蛋白质和酚类物质共同存在于植物细胞的受限空间中，导致它们之间发生反应，形成新的共价键合的复杂分子。这种反应在植物材料的储存和加工过程中广泛观察到。然而，新的复杂分子的性质及其物理化学性质在很大程度上是未知的。因此，我们研究了葵花蛋白分离物（SFPI，蛋白质含量 85wt%）与葵花籽油细胞受限空间中占主导地位的酚类物质（绿原酸，CGA）之间形成的共价键合复合物的结构特征。结果表明，键合效率随 SFPI：CGA 比例的变化而呈现最大值。此外，CGA 与蛋白质的结合导致蛋白质的二级和三级结构发生变化。还表明，酚类物质与蛋白质结合紧密，导致多肽链之间形成新的交联。结果，像α-螺旋和β-折叠这样的二级结构减少，这反过来又导致更多无序的结构域和蛋白质三级结构的后续修饰。这些发现对于建立未来利用植物材料提取高质量蛋白质和酚类物质的方案具有重要意义，并深入了解这些成分在加工过程中所承受的影响。
