Characterization of the vitamin E-binding properties of human plasma afamin

被引:99
作者
Voegele, AF
Jerkovic, L
Wellenzohn, B
Eller, P
Kronenberg, F
Liedl, KR
Dieplinger, H [1 ]
机构
[1] Vitateq Biotechnol GmbH, Innsbruck, Austria
[2] Univ Innsbruck, Dept Theoret Chem, A-6020 Innsbruck, Austria
[3] Univ Innsbruck, Inst Med Biol & Human Genet, A-6020 Innsbruck, Austria
关键词
D O I
10.1021/bi026513v
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Human plasma afamin, the fourth member of the albumin gene family, is shown to be a specific binding protein for vitamin E. A radio ligand-binding assay followed by Scatchard and Hill analysis are used to show that afamin has a binding affinity for both alpha-tocopherol and gamma-tocopherol, two of the most important forms of vitamin E, in vitro. The binding-dissociation constant was determined to be 18 muM, indicating that afamin plays a role as vitamin E carrier in body fluids such as human plasma and follicular fluid under physiological conditions. Additionally, we demonstrate that afamin has multiple binding sites for both alpha- and gamma-tocopherol. Due to the large binding capacity of afamin for vitamin E, it might take over the role of vitamin E transport in body fluids under conditions where the lipoprotein system is not sufficient for vitamin E transport. To confirm the experimental results, we performed homology modeling and docking calculations on the predicted tertiary structure, which showed coincidence between calculated and in vitro results.
引用
收藏
页码:14532 / 14538
页数:7
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