Conformation and Aggregation of Human Serum Albumin in the Presence of Green Tea Polyphenol (EGCg) and/or Palmitic Acid
Conformation and Aggregation of Human Serum Albumin in the Presence of Green Tea Polyphenol (EGCg) and/or Palmitic Acid
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DOI：
10.3390/biom9110705
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发表时间：
2019-11-01
期刊：
影响因子：
5.5
通讯作者：
Hagerman, Ann E.
中科院分区：
文献类型：
--
作者：
Sun, Xiaowei;Ferguson, Haley N.;Hagerman, Ann E.
多酚如表没食子儿茶素没食子酸酯（EGCg）作为植物性食品和饮料的成分摄入时，可能具有预防某些慢性疾病的作用。人血清白蛋白（HSA）是一种多结构域蛋白，其结合各种配体并有助于它们在循环系统中的运输、分布和代谢。在本研究中，HSA-EGCg相互作用的存在或不存在的脂肪酸进行了研究。福斯特共振能量转移（FRET）被用来确定在蛋白质与和没有EGCg和棕榈酸（PA）的结构域间和结构域内的距离。通过用7-（二乙基氨基）-4-甲基香豆素3-马来酰亚胺（CPM）标记Cys-34，可以建立结构域IIA的Trp-214和结构域IA的CPM-Cys-34之间的距离。少量的PA减少了距离，而大量的PA增加了距离高达5.4埃。EGCg使HSA和HSA-PA中的域间距离分别增加至2.8和7.6埃。我们得出结论，PA影响蛋白质构象更显着相比，EGCg。圆二色性（CD）表明EGCg对蛋白质二级结构的影响比PA更显著。PA对HSA的α-螺旋含量影响不大，而EGCg以剂量依赖性方式降低HSA的α-螺旋含量。此外，EGCg降低HSA和HSA-PA中的α-螺旋含量至相同水平。动态光散射（DLS）数据显示，PA和EGCg增加HSA聚集。EGCg增加HSA聚集更显着，并促进形成更异质性的聚集体。这些作用中的任何一种都可能影响血清白蛋白转运和稳定配体（包括EGCg和其他多酚）的能力。
Polyphenols such as epigallocatechin gallate (EGCg) may have roles in preventing some chronic diseases when they are ingested as components of plant-based foods and beverages. Human serum albumin (HSA) is a multi-domain protein that binds various ligands and aids in their transport, distribution, and metabolism in the circulatory system. In the present study, the HSA-EGCg interaction in the absence or presence of fatty acid has been investigated. Forster resonance energy transfer (FRET) was used to determine inter- and intra-domain distances in the protein with and without EGCg and palmitic acid (PA). By labeling Cys-34 with 7-(diethyl amino)-4-methylcoumarin 3-maleimide (CPM), the distance between Trp-214 at domain IIA and CPM-Cys-34 at domain IA could be established. A small amount of PA decreased the distance, while a large amount increased the distance up to 5.4 angstrom. EGCg increased the inter-domain distance in HSA and HSA-PA up to 2.8 and 7.6 angstrom, respectively. We concluded that PA affects protein conformation more significantly compared to EGCg. Circular dichroism (CD) established that EGCg affects protein secondary structure more significantly than PA. PA had little effect on the alpha-helix content of HSA, while EGCg decreased the alpha-helix content in a dose-dependent fashion. Moreover, EGCg decreased alpha-helix content in HSA and HSA-PA to the same level. Dynamic light scattering (DLS) data revealed that both PA and EGCg increased HSA aggregation. EGCg increased HSA aggregation more significantly and promoted formation of aggregates that were more heterogenous. Any of these effects could impact the ability of serum albumin to transport and stabilize ligands including EGCg and other polyphenols.