Li Tian, Jiao Ruonan, Ma Jiaqi, Zang Jiachen, Zhao Guanghua, Zhang Tuo
College of Food Science and Nutritional Engineering, Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, China Agricultural University Beijing 100083 China
RSC Adv. 2022 Aug 1;12(33):21122-21128. doi: 10.1039/d2ra03565k. eCollection 2022 Jul 21.
Zinc plays a vital role in structural, catalysis, and signal regulation in the human body. Zinc deficiency leads to the dysfunction of many organs and immunity systems. Diet proteins have distinct effects on zinc uptake. However, the mechanisms are uncovered. Here we select three principal components from whey protein: alpha-lactalbumin, beta-lactoglobulin, and bovine serum albumin, which bind with zinc at different affinities, to evaluate the relationship between their potential zinc uptake and protein binding. The experimental data shows that beta-lactoglobulin could promote zinc uptake, alpha-lactalbumin has minor effects, whereas bovine serum albumin reduced zinc uptake in Caco-2 cell lines. Zinc binding effects on protein structure were thoroughly inspected through fluorescent spectroscopy and X-ray crystallography. Isothermal titration calorimetry revealed that three proteins have different binding affinities toward zinc ions. We speculate that protein binding eliminates toxic effects from free zinc, and the binding strength dominates zinc uptake.
锌在人体的结构、催化和信号调节中起着至关重要的作用。锌缺乏会导致许多器官和免疫系统功能失调。膳食蛋白质对锌的吸收有不同影响。然而，其机制尚未明确。在此，我们从乳清蛋白中选取三种主要成分：α-乳白蛋白、β-乳球蛋白和牛血清白蛋白，它们与锌具有不同的亲和力，以评估它们潜在的锌吸收与蛋白质结合之间的关系。实验数据表明，β-乳球蛋白可促进锌吸收，α-乳白蛋白影响较小，而牛血清白蛋白在Caco-2细胞系中降低了锌吸收。通过荧光光谱和X射线晶体学全面研究了锌结合对蛋白质结构的影响。等温滴定量热法显示，三种蛋白质对锌离子具有不同的结合亲和力。我们推测，蛋白质结合消除了游离锌的毒性作用，且结合强度主导锌的吸收。
