Many viruses, including beta coronaviruses, have been shown to interact with human glycosaminoglycans, which are negatively-charged polysaccharides.  Studies suggest that SARS-CoV-2 can bind to the glycosaminoglycans heparan sulphate and heparin.  Additionally, it is thought. that heparin can prevent the virus from entering host cells while heparan sulphates facilitate infection by keeping SARS-CoV-2 S protein in its open conformation which allows it to interact with ACE2 receptors and TMPRSS2.

Glycosaminoglycans in the Pathogenesis of COVID-19

Heparin and heparan sulfate are structurally similar glycosaminoglycans that are physiologically relevant and have been used as pharmacological targets, especially in regards to cancer.  Heparin interacts with the protein antithrombin III (ATIII) and causes a conformation change that increases its ability to inhibit coagulation factors.  Consequently, heparin is used as an anticoagulant.  Heparan sulfate is involved in many processes.  It is notably involved in cell-to-cell extracellular membrane organization - the process in which cells adhere together - and cell proliferation via growth factor signaling.  These roles make it and its related enzymes key targets for drugs meant to prevent cancer metastasis.  

Heparin and Heparan Sulfate

Glycosaminoglycans are negatively charged polysaccharides that are composed of a repeating disaccharides subunit.  They are involved in cell hydration, structure, and cell signaling.  Glycosaminoglycans can be categorized by their repeating subunit:

- heparin/heparan sulfate
- chondroitin sulfate/dermatan sulfate
- keratan sulfate
- hyaluronic acid

Michigan State University

Polysaccharides are carbohydrates that are made up of long chains of monosaccharides which could be different kinds. The chain may contain branches. Polysaccharides play important structural and storage roles in cells.

Polysaccharides (glycans)

Casale, J., & Crane, J. S. (2019). Biochemistry, Glycosaminoglycans.
https://www.ncbi.nlm.nih.gov/books/NBK544295/#:~:text=Glycosaminoglycans%20(GAGs)%2C%20also%20known,determined%20by%20their%20molecular%20structure.

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