Interaction between endogenous circulating sulfated-glycosaminoglycans and plasma proteins

Area of Science:

• Biochemistry
• Proteomics
• Glycobiology

Background:

• Plasma glycosaminoglycans (GAGs) are complex carbohydrates with diverse biological roles.
• The interactions between GAGs and plasma proteins are not fully understood.
• Investigating these interactions is crucial for understanding plasma composition and function.

Purpose of the Study:

• To investigate the interactions between endogenous glycosaminoglycans and plasma proteins in murine plasma.
• To determine the nature of these interactions (covalent vs. non-covalent) and the specific proteins involved.
• To elucidate the role of lipids and protein presence in modulating GAG properties.

Main Methods:

• Gel chromatography and autoradiography to identify GAG-protein associations.
• Sepharose CL-6B chromatography after proteolysis or beta-elimination to assess covalent binding.
• Hydrophobic interaction chromatography to investigate lipid involvement.
• Ion-exchange chromatography to evaluate the impact of proteins on GAG anionic properties.

Main Results:

• 35S-labelled GAGs co-eluted with various plasma proteins, including albumin and globulins (alpha 1, alpha 2, beta), but not gamma globulins.
• Evidence suggests covalent binding of GAG chains to proteins.
• Lipids appear to mediate supramolecular assembly of GAGs with proteins.
• Strong non-covalent interactions hinder the extraction of 'free' GAGs.
• Plasma proteins reduce the anionic properties of GAGs.

Conclusions:

• Endogenous plasma GAGs are extensively bound to plasma proteins through both covalent and non-covalent interactions.
• Lipids play a role in the complexation of GAGs and proteins.
• These interactions significantly affect GAG extractability and properties within the plasma environment.