| Abstract
| - Human plasma afamin, the fourth member of the albumin gene family, is shown to be a specificbinding protein for vitamin E. A radio ligand-binding assay followed by Scatchard and Hill analysis areused to show that afamin has a binding affinity for both α-tocopherol and γ-tocopherol, two of the mostimportant forms of vitamin E, in vitro. The binding-dissociation constant was determined to be 18 μM,indicating that afamin plays a role as vitamin E carrier in body fluids such as human plasma and follicularfluid under physiological conditions. Additionally, we demonstrate that afamin has multiple binding sitesfor both α- and γ-tocopherol. Due to the large binding capacity of afamin for vitamin E, it might takeover the role of vitamin E transport in body fluids under conditions where the lipoprotein system is notsufficient for vitamin E transport. To confirm the experimental results, we performed homology modelingand docking calculations on the predicted tertiary structure, which showed coincidence between calculatedand in vitro results.
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