Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Cuajimalpa, D.F. 05300, Mexico.
Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Cuajimalpa, D.F. 05300, Mexico.
Food Chem. 2016 Dec 15;213:431-439. doi: 10.1016/j.foodchem.2016.06.105. Epub 2016 Jun 30.
In this study, the interaction between the flavonoid pelargonidin and dairy proteins: β-lactoglobulin (β-LG), whey protein (WPI), and caseinate (CAS) was investigated. Fluorescence experiments demonstrated that pelargonidin quenched milk proteins fluorescence strongly. However, the protein secondary structure was not significantly affected by pelargonidin, as judged from far-UV circular dichroism. Analysis of fluorescence data indicated that pelargonidin-induced quenching does not arise from a dynamical mechanism, but instead is due to protein-ligand binding. Therefore, quenching data were analyzed using the model of independent binding sites. Both β-LG and CAS, but not WPI, showed hyperbolic binding isotherms indicating that these proteins firmly bound pelargonidin at both pH 7.0 and 3.0 (binding constants ca. 1.0×10(5) at 25.0°C). To investigate the underlying thermodynamics, binding constants were determined at 25.0, 35.0, and 45.0°C. These results pointed to binding processes that depend on the structural conformation of the milk proteins.
在这项研究中，研究了类黄酮锦葵色素与乳蛋白（β-乳球蛋白（β-LG）、乳清蛋白（WPI）和酪蛋白（CAS））之间的相互作用。荧光实验表明，锦葵色素强烈猝灭了牛奶蛋白的荧光。然而，从远紫外圆二色性判断，锦葵色素并没有显著影响蛋白质的二级结构。荧光数据分析表明，锦葵色素诱导的猝灭不是来自动力学机制，而是由于蛋白质-配体结合。因此，使用独立结合位点模型分析猝灭数据。β-LG 和 CAS（但不是 WPI）都显示出双曲线结合等温线，表明这些蛋白质在 pH 7.0 和 3.0 时都能牢固地结合锦葵色素（在 25.0°C 时结合常数约为 1.0×10(5)）。为了研究潜在的热力学，在 25.0、35.0 和 45.0°C 下确定了结合常数。这些结果表明结合过程取决于乳蛋白的结构构象。
