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Electrospray ionisation analysis of human fibrinogen
1Molecular Pathology Laboratory, Christchurch Hospital, New Zealand.
Thrombosis and Haemostasis
|October 6, 1997
Summary
This study used mass spectrometry to analyze human fibrinogen, revealing variations in its Bbeta and gamma chains due to sialic acid loss. Thrombin cleavage confirmed peptide losses, and factor XIII induced dimer formation.
Area of Science:
- Biochemistry
- Proteomics
- Analytical Chemistry
Background:
- Fibrinogen is a key glycoprotein in human plasma involved in blood clotting.
- Understanding fibrinogen's structure and variations is crucial for diagnostics and therapeutics.
Purpose of the Study:
- To characterize the polypeptide chains of human fibrinogen using mass spectrometry.
- To identify and quantify variations in fibrinogen isoforms.
- To analyze the effects of thrombin cleavage on fibrinogen chain masses.
Main Methods:
- Purification of fibrinogen from human plasma.
- Electrospray ionization mass spectrometry (ESI-MS) for polypeptide chain analysis.
- Incubation with thrombin and factor XIII to observe enzymatic modifications.
Main Results:
- Identified predominant isoforms of Bbeta and gamma chains lacking a sialic acid residue.
- Observed significant mass variation in the A alpha chain, likely due to phosphorylation.
- Confirmed mass changes consistent with B peptide loss from the beta chain and A peptide loss from the alpha chain upon thrombin treatment.
- Detected gamma-gamma dimers formed by factor XIII action.
Conclusions:
- Human fibrinogen exhibits isoform heterogeneity, particularly in Bbeta and gamma chains, related to sialic acid content.
- Post-translational modifications like phosphorylation contribute to A alpha chain mass variability.
- Mass spectrometry provides precise characterization of fibrinogen structure and its modifications during coagulation.