Structural characterization of human liver heparan sulfate

Area of Science:

• Biochemistry
• Glycobiology
• Structural Biology

Background:

• Heparan sulfate (HS) is a glycosaminoglycan (GAG) with diverse biological roles.
• Distinguishing HS from heparin is crucial due to their differing biological activities.
• Human liver HS has not been extensively characterized structurally and functionally.

Purpose of the Study:

• To isolate, purify, and structurally characterize human liver heparan sulfate.
• To compare the structural and functional properties of human liver HS with heparin and other HS sources.

Main Methods:

• Isolation and purification of glycosaminoglycans from human liver.
• Structural confirmation using Nuclear Magnetic Resonance (NMR) spectroscopy (1D and 2D).
• Enzymatic depolymerization and analysis of unsaturated disaccharides via High-Performance Liquid Chromatography (HPLC) with fluorescence detection.
• Assessment of antithrombin-mediated anti-factor Xa activity.

Main Results:

• Successful isolation and purification of human liver heparan sulfate confirmed by NMR.
• Human liver HS exhibits a reduced content of unsulfated disaccharides and an elevated average sulfation level compared to heparin.
• Anticoagulant activity (anti-factor Xa) of human liver HS is lower than pharmaceutical heparin but comparable to standard porcine intestinal HS.
• Human liver HS shows a higher degree of sulfation than HS from porcine liver or HepG2 cells.

Conclusions:

• The isolated glycosaminoglycan is definitively human liver heparan sulfate, not heparin.
• Human liver HS possesses distinct structural and functional characteristics, including higher sulfation.
• Its anticoagulant activity is moderate, suggesting specific biological roles beyond anticoagulation.