Dynamic light scattering studies on hydrodynamic properties of fibrinogen-fibronectin complex

Area of Science:

• Biochemistry
• Rheumatology
• Materials Science

Background:

• Patients with rheumatoid arthritis (RA) exhibit unique plasma cryogels.
• These cryogels are high molecular weight insoluble complexes formed at low temperatures.

Purpose of the Study:

• To isolate and characterize the fibrinogen-fibronectin complex from RA plasma cryogels.
• To investigate the hydrodynamic properties and temperature-dependent behavior of this complex.

Main Methods:

• Cryogel isolation from heparinized RA plasma via cold incubation.
• Solubilization at 37°C and purification by affinity chromatography (gelatin-Sepharose 4B).
• Dynamic light scattering (DLS) to analyze hydrodynamic properties (diffusion coefficients) under varying temperature and NaCl concentrations.

Main Results:

• A 1:1 complex of fibrinogen and fibronectin was purified.
• Diffusion coefficients decreased with increasing NaCl concentration, indicating a more compact form at low ionic strength due to fibronectin conformational changes.
• The complex remained stable between 20-37°C but showed decreased diffusion at 12°C and 40°C.
• Fibrinogen denaturation observed at 40°C.
• Complex aggregation into higher structures occurred at 15°C, reversibly.

Conclusions:

• The fibrinogen-fibronectin complex from RA cryogels displays distinct hydrodynamic properties and temperature-dependent aggregation.
• Conformational changes in fibronectin influence complex compactness.
• The reversible aggregation suggests a dynamic equilibrium influenced by temperature and ionic conditions.