Tannins are compounds with antinutrient properties that hinder food digestibility, prejudicing human and animal nutrition. This work aimed to evaluate the negative effects of tannic acid on Kluyveromyces lactis β-galactosidase catalytic activity and correlate these changes with the protein structure. β-Galactosidase activity decreased in the presence of tannins, which caused changes to the structure of the enzyme, as demonstrated by circular dichroism. It was verified that tannin binds to the protein by a static mechanism. Additionally, isothermal titration calorimetry suggested that tannic acid modified the molecular interaction between β-galactosidase and o-nitrophenyl-β-d-galactoside, reducing their affinity and prejudicing the protein activity. This study helps to understand the effects of tannins on the β-galactosidase structure and how they are related to the enzyme catalytic activity. The alterations in the conformation and activity of the enzyme should be taken into consideration when dairy products are consumed with tannin-rich food.

单宁是具有抗营养特性的化合物，会阻碍食物的消化，损害人类和动物的营养。这项工作旨在评估单宁酸对乳酸克鲁维酵母β-半乳糖苷酶催化活性的负面影响，并将这些变化与蛋白质结构相关联。单宁存在时，β-半乳糖苷酶活性降低，这导致了酶结构的改变，这通过圆二色性证明。已证实单宁通过静态机制与蛋白质结合。此外，等温滴定热法表明单宁酸修饰了β-半乳糖苷酶和邻-硝基苯基-β- d之间的分子相互作用。-半乳糖苷，降低它们的亲和力并损害蛋白质活性。这项研究有助于了解单宁对β-半乳糖苷酶结构的影响以及它们与酶催化活性的关系。当乳制品与富含单宁的食物一起食用时，应考虑酶构象和活性的改变。