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Keywords:

  • human serum albumin;
  • α-tocopherol;
  • thermodynamics;
  • FA3–FA4 cleft;
  • binding mode

Abstract

Given the ability of human serum albumin (HSA) to bind hydrophobic ligands, the binding mode of α-tocopherol, the most representative member of the vitamin E family, is reported. α-Tocopherol binds to HSA with K equation image = (7.0 ± 3.0) × 10−6 M (pH 7.2, 25.0°C). Competitive and allosteric modulation of α-tocopherol binding to full-length and truncated (Asp1-Glu382) HSA by endogenous and exogenous ligands suggests that it accommodates preferentially in the FA3–FA4 site. As HSA is taken up into cells, colocalizes with the α-tocopherol transfer protein, and contributes to ligand secretion via ABCA1, it might participate in the distribution of α-tocopherol between plasma, cells, and tissues. © 2013 BioFactors, 2013