BMS149 LEC07: Glycosaminoglycans (GAGs)

What is the primary association of glycosaminoglycans (GAGs)?

What is the structure of glycosaminoglycans (GAGs)?

What is the composition of the repeating disaccharide units in glycosaminoglycans?

Where are glycosaminoglycans (GAGs) primarily present?

What type of acid is commonly found in glycosaminoglycans (GAGs)?

What is the main association of glycosaminoglycans?

What is the function of hyaluronic acid?

Which type of GAG is associated mainly with cell membrane and plays an important role in cell membrane receptors and cell-cell interactions?

What can restore the viscoelastic properties of synovial fluid in osteoarthritic joints?

Which molecule has a protein component making up 5-10% of the molecule and a carbohydrate component making up 95% of the molecule?

What is the main function of heparin?

What is the role of keratan sulfate in the body?

Which type of GAG is involved in cell membrane receptors and cell-cell interactions?

What is the primary function of chondroitin sulfate?

What can restore the viscoelastic properties of synovial fluid in osteoarthritic joints?

Which molecule has a protein component making up 5-10% of the molecule and a carbohydrate component making up 95% of the molecule?

Glycosaminoglycans (GAGs) are large complexes of negatively charged heteropolysaccharide chains, primarily found in the extracellular matrix (ECM).
GAGs are formed by covalently linking to a protein core, creating proteoglycans.
Proteoglycans are characterized by their large carbohydrate (GAG) chains and a small protein core.
Proteoglycans play various roles in the body, including:
- Acting as shock absorbers and lubricants (e.g., hyaluronic acid in synovial fluid)
- Providing structural support and contributing to the gel-like consistency of the ECM.
There are eight types of GAGs:
- Sulfate-free GAGs: hyaluronic acid
- Sulfated GAGs: chondroitin sulfate, keratan sulfate, dermatan sulfate, heparan sulfate, heparin.
GAGs and proteoglycans serve various functions in the body:
- Hyaluronic acid: lubricant and shock absorbent in synovial fluid, involved in wound healing, used in clinical applications such as injections for osteoarthritis pain.
- Heparin: anticoagulant.
- Keratan sulfate: important for corneal transparency.
- Heparan sulfate: associated with cell membranes and play an important role in cell membrane receptors and cell-cell interactions.
Proteoglycans and glycoproteins differ in their protein and carbohydrate components:
- Proteoglycans: protein component (5-10%), carbohydrate component (95%), large carbohydrate chains called GAGs.
- Glycoproteins: protein component (up to 99%), carbohydrate components (up to 55%), short chain constituent sugars, often contain uronic acid, examples include hyaluronic acid, dermatan sulfate.
Most proteins are glycoproteins, but proteoglycans contain a larger proportion of carbohydrate components in the form of GAGs.

Prepare for the Fall 2023 lecture on Glycosaminoglycans (GAGs) by testing your knowledge on their structure, types, proteoglycan structure, functions, comparison with glycoproteins, and the biochemical basis of mucopolysaccharidosis.