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Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Binding sites for the (Hg-Se) complex on selenoprotein P
K T Suzuki1, C Sasakura, S Yoneda
1Faculty of Pharmaceutical Sciences, Chiba University, Inage, Japan. ktsuzuki@p.chiba-u.ac.jp
Biochimica Et Biophysica Acta
|January 27, 1999
Summary
Mercury and selenium form complexes that bind to selenoprotein P in the bloodstream. This binding occurs at specific sites on selenoprotein P, involving unique amino acid groups.
Area of Science:
- Biochemistry
- Environmental Toxicology
- Analytical Chemistry
Background:
- Mercury (Hg) and selenium (Se) interactions are crucial in biological systems.
- Selenoprotein P (Sel P) is a key selenium-binding protein in plasma.
- The complex formation between Hg, Se, and Sel P influences their toxicological and physiological roles.
Purpose of the Study:
- To elucidate the binding mechanism of mercury-selenium complexes to Sel P.
- To identify the specific binding sites and stoichiometry of the interaction.
- To differentiate the binding of Hg-Se complexes from free Hg2+ or selenide.
Main Methods:
- Competitive binding assays using polymeric and monomeric amino acids.
- High-performance liquid chromatography-inductively coupled argon plasma-mass spectrometry (HPLC-ICP-MS) for detecting Hg, selenite-Se, and Sel P-Se.
- Quantitative analysis of complex formation and binding stoichiometry.
Main Results:
- The (Hg-Se)n complex specifically binds to Sel P, unlike Hg2+ or selenide.
- Binding occurs at unique sites on Sel P, involving cationic (imidazolyl) and anionic (selenol) groups.
- The estimated stoichiometry is approximately 100 Hg-Se units per complex (n=100) binding to 35 sites (m=35) on Sel P.
Conclusions:
- The interaction between mercury and selenium in blood involves the formation of [(Hg-Se)100]35-Sel P complexes.
- Specific binding sites on Sel P, characterized by imidazolyl and selenol groups, mediate this interaction.
- Understanding this mechanism is vital for assessing the toxicokinetics and toxicodynamics of mercury and selenium.
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