Zinc modulates thrombin adsorption to fibrin

Area of Science:

• Biochemistry
• Hematology
• Protein-ligand interactions

Background:

• Thrombin plays a crucial role in hemostasis and thrombosis.
• Understanding factors modulating thrombin's interaction with fibrin is vital for hemostasis research.
• The influence of divalent metal ions on thrombin-fibrin binding requires further elucidation.

Purpose of the Study:

• To investigate the effect of zinc (II) and calcium (II) ions on the adsorption of human thrombin to fibrin.
• To determine the concentration-dependent effects of Zn(II) on thrombin-fibrin binding.
• To compare the modulatory effects of Zn(II) and Ca(II) on thrombin adsorption.

Main Methods:

• Utilized high-affinity thrombin immobilized on Sepharose.
• Quantified thrombin binding to fibrin using 125I-labelled thrombin.
• Assessed thrombin activity via chromogenic substrate and clotting time assays.
• Controlled experiments evaluated fibrinogen clottability and fibrin cross-linking.

Main Results:

• Zn(II) at concentrations >100 µmol/L decreased thrombin binding to fibrin in a dose- and time-dependent manner.
• Lower Zn(II) concentrations enhanced thrombin adsorption to fibrin.
• Ca(II) alone or with Zn(II) showed minimal effect, except at higher concentrations (7.5–15 mmol/L) where it decreased binding.
• Zn(II) did not affect fibrinogen clottability, and Ca(II) results were not influenced by fibrin cross-linking.

Conclusions:

• Zinc (II) ions are highly effective in modulating thrombin adsorption to fibrin.
• Unlike Ca(II), Zn(II) exhibits a complex, concentration-dependent effect on thrombin-fibrin interactions.
• Findings suggest a potential role for Zn(II) in regulating coagulation processes.