Centro de Investigação em Química, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
J Agric Food Chem. 2010 Nov 24;58(22):11924-31. doi: 10.1021/jf1023356. Epub 2010 Nov 3.
The interactions between the digestive protease trypsin type IX-S from porcine pancreas and grape seed procyanidins were monitorized by fluorescence quenching, dynamic light scattering, nephelometry, circular dichroism, and enzymatic inhibition assay. This work reports that the inhibition of trypsin activity by grape seed procyanidins and the respective quenching of intrinsic protein fluorescence are closely related. These two phenomena increase with the molecular weight of the tested procyanidins. The interaction between procyanidins and enzyme was shown to involve a specific interaction as inferred from the fluorescence assays. It was also shown by fluorescence spectroscopy that the binding of procyanidin molecules to the enzyme does not induce significant structural modifications. A relationship between aggregate formation, using dynamic light scattering and nephelometry, and fluorescence quenching was observed with maxima achieved for similar stoichiometric ratios. The binding of procyanidins to trypsin affects only slightly protein structure as seen by circular dichroism.
采用荧光猝灭、动态光散射、消光比浊、圆二色性和酶抑制测定法监测来自猪胰的消化蛋白酶胰蛋白酶 IX-S 与葡萄籽原花青素之间的相互作用。本工作报道，葡萄籽原花青素对胰蛋白酶活性的抑制作用及其固有蛋白质荧光的相应猝灭作用密切相关。这两种现象都随测试原花青素的分子量增加而增加。荧光测定表明，原花青素与酶之间的相互作用涉及特异性相互作用。荧光光谱还表明，原花青素分子与酶的结合不会引起显著的结构修饰。用动态光散射和消光比浊法观察到聚集形成与荧光猝灭之间的关系，最大猝灭发生在相似的化学计量比。正如圆二色性所示，原花青素与胰蛋白酶的结合仅轻微影响蛋白质结构。
