Yang Rui, Liu Yuqian, Meng Demei, Chen Zhiyu, Blanchard Christopher L, Zhou Zhongkai
Key Laboratory of Food Nutrition and Safety, Ministry of Education, School of Food Engineering and Biotechnology, Tianjin University of Science and Technology , Tianjin 300457, China.
Tianjin Food Safety & Low Carbon Manufacturing Collaborative Innovation Center , Tianjin 300457, China.
J Agric Food Chem. 2017 Feb 22;65(7):1410-1419. doi: 10.1021/acs.jafc.6b04671. Epub 2017 Feb 13.
The 8 nm diameter cavity endows the ferritin cage with a natural space to encapsulate food components. In this work, urea was explored as a novel medium to facilitate the formation of ferritin-polyphenol co-assemblies. Results indicated that urea (20 mM) could expand the 4-fold channel size of apo-red bean ferritin (apoRBF) with an increased initial iron release rate υ (0.22 ± 0.02 μM min) and decreased α-helix content (5.6%). Moreover, urea (20 mM) could facilitate the permeation of EGCG into the apoRBF without destroying the ferritin structure and thus form ferritin-EGCG co-assemblies (FECs) with an encapsulation ratio and loading capacity of 17.6 and 2.1% (w/w), respectively. TEM exhibited that FECs maintained a spherical morphology with a 12 nm diameter in size. Fluorescence analysis showed that urea intervention could improve the binding constant K [(1.22 ± 0.8) × 10 M] of EGCG to apoRBF. Furthermore, the EGCG thermal stability was significantly improved (20-60 °C) compared with free EGCG. Additionally, this urea-involved method was applicable for chlorogenic acid and anthocyanin encapsulation by the apoRBF cage. Thus, urea shows potential as a novel potential medium to encapsulate and stabilize bioactive polyphenols for food usage based on the ferritin protein cage structure.
直径8纳米的空腔赋予铁蛋白笼一个天然空间来封装食品成分。在这项工作中，探索了尿素作为一种新型介质来促进铁蛋白-多酚共组装体的形成。结果表明，尿素（20 mM）可使脱辅基红豆铁蛋白（apoRBF）的4倍通道尺寸扩大，初始铁释放速率υ增加（0.22±0.02 μM/min），α-螺旋含量降低（5.6%）。此外，尿素（20 mM）可促进表没食子儿茶素没食子酸酯（EGCG）渗透到apoRBF中而不破坏铁蛋白结构，从而形成铁蛋白-EGCG共组装体（FECs），其包封率和负载量分别为17.6%和2.1%（w/w）。透射电子显微镜（TEM）显示，FECs保持直径为12纳米的球形形态。荧光分析表明，尿素干预可提高EGCG与apoRBF的结合常数K [（1.22±0.8）×10 M]。此外，与游离EGCG相比，EGCG的热稳定性显著提高（20 - 60℃）。此外，这种涉及尿素的方法适用于apoRBF笼对绿原酸和花青素的封装。因此，基于铁蛋白笼结构，尿素显示出作为一种新型潜在介质用于封装和稳定生物活性多酚以供食品使用的潜力。
