Sulfatide bilayers as a surface for contact activation in human plasma

Area of Science:

• Lipid biochemistry
• Hemostasis
• Biophysical chemistry

Background:

• Sulfatides are known to influence biological processes.
• Contact activation is a critical initial step in the blood coagulation cascade.
• The structural requirements for sulfatide-mediated contact activation are not fully understood.

Purpose of the Study:

• To investigate the relationship between sulfatide structure and their ability to promote contact activation in human plasma.
• To characterize the different structural forms of sulfatides generated under various conditions.
• To identify the specific sulfatide structures responsible for initiating contact activation.

Main Methods:

• Gel permeation chromatography (GPC) for size exclusion.
• Freeze fracture electron microscopy (FFEM) for structural visualization.
• Vortexing and sonication for liposome/vesicle formation.
• Assay of contact activation promoting activity.

Main Results:

• Sulfatides form bilayer structures essential for promoting contact activation.
• Vortexing at 70°C yielded large liposomes (2-5 μm) with activity.
• Sonication produced smaller vesicles (400-2000 Å) that also exhibited activity.
• Homogeneous small unilamellar vesicles (500 Å) were obtained using Sepharose 2B chromatography.

Conclusions:

• The ability of sulfatides to promote contact activation is directly linked to their capacity to form bilayer structures.
• Different preparation methods yield sulfatide structures with varying sizes and activities.
• Specific vesicle sizes, particularly small unilamellar vesicles, are effectively generated for studying their procoagulant role.