Influence of the Galloyl Moiety in Tea Catechins on Binding Affinity for Human Serum Albumin
Influence of the Galloyl Moiety in Tea Catechins on Binding Affinity for Human Serum Albumin
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DOI：
10.3177/jnsv.56.331
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发表时间：
2010-10-01
影响因子：
1.6
通讯作者：
Nakayama, Tsutomu
中科院分区：
文献类型：
--
作者：
Minoda, Kanako;Ichikawa, Tatsuya;Nakayama, Tsutomu
绿茶提取物中主要的儿茶素有(-)-表儿茶素(EC)、(-)-表儿茶素(EGC)、(-)-表儿茶素没食子酸酯(CG)和(-)-表儿茶素没食子酸酯(EGCG)。最近的研究表明，儿茶素在血液中与人血清白蛋白(HSA)形成络合物，它们与HSA结合的亲和力的差异被认为调节了它们的生物利用度。在本研究中，我们在石英晶体微天平(QCM)上对儿茶素与人血清白蛋白的相互作用进行了动力学研究。由QCM频率变化得到的结合常数表明，心电和EGCG与HSA的相互作用比EC和EGC强100倍。此外，通过天然凝胶电泳/印迹和氧化还原循环染色对这些儿茶素的比较表明，在磷酸盐缓冲液中，CG和EGCG与HSA的结合亲和力高于EC和EGC。这些观察表明，与没有没食子酸基的儿茶素相比，具有没食子酸基的儿茶素与HSA的结合亲和力更高。
The major catechins of green tea extract are (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg). Recent research has indicated that catechins form complexes with human serum albumin (HSA) in blood, and differences in their binding affinity toward HSA are believed to modulate their bioavailability. In this study, we kinetically investigated the interaction between the catechins and HSA immobilized on a quartz-crystal microbalance (QCM). The association constants obtained from the frequency changes of QCM revealed interactions of ECg and EGCg with HSA that are 100 times stronger than those of EC and EGC. Furthermore, comparisons of these catechins by native-gel electrophoresis/blotting with redox-cycling staining revealed that, in a phosphate buffer, ECg and EGCg have a higher binding affinity toward HSA than EC and EGC. These observations indicate that catechins with a galloyl moiety have higher binding affinities toward HSA than catechins lacking a galloyl moiety.