Heparin interacts with a selenoprotein in human plasma

Area of Science:

• Biochemistry
• Analytical Chemistry
• Clinical Chemistry

Background:

• Selenium is an essential trace element crucial for various physiological functions.
• The distribution and binding of selenium in human plasma can be influenced by experimental conditions.
• Previous studies reported discrepancies in selenium distribution, potentially due to anticoagulant use.

Purpose of the Study:

• To investigate the interaction between heparin and selenium-containing proteins in human plasma.
• To elucidate the cause of differing selenium distribution patterns observed with various anticoagulants.

Main Methods:

• Gel filtration chromatography (Sephadex G-150) of human serum and heparinized plasma.
• Analysis of selenium-containing peaks and their elution profiles (Kav values).
• Assessment of heparin's effect using protamine sulfate.

Main Results:

• A major selenium-containing protein peak showed a different elution profile (Kav 0.19 in serum vs. 0.01 in heparinized plasma).
• This shift indicated a strong interaction between heparin and the selenium-binding protein.
• Protamine sulfate, a heparin antagonist, abolished the heparin-induced shift.
• The identified heparin-interacting protein was distinct from glutathione peroxidase.

Conclusions:

• Heparin in plasma directly interacts with a major selenium-containing protein.
• This interaction alters the protein's apparent size during gel filtration chromatography.
• The findings reconcile previous discrepancies in plasma selenium distribution related to anticoagulant choice.