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Questions and Answers
What is the primary amino acid found in every third position of collagen's triple helix structure?
What is the primary amino acid found in every third position of collagen's triple helix structure?
Which types of collagen make up over 90% of the collagen found in the human body?
Which types of collagen make up over 90% of the collagen found in the human body?
Which of the following statements about collagen is true?
Which of the following statements about collagen is true?
What role do proline and hydroxyproline play in the structure of collagen?
What role do proline and hydroxyproline play in the structure of collagen?
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Collagen can be classified into different types. What distinguishes type IV collagen from types I, II, and III?
Collagen can be classified into different types. What distinguishes type IV collagen from types I, II, and III?
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Which amino acids most often occupy the positions represented by X and Y in the characteristic sequence of collagen?
Which amino acids most often occupy the positions represented by X and Y in the characteristic sequence of collagen?
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What type of proteins are collagen and elastin classified as?
What type of proteins are collagen and elastin classified as?
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Which of the following is a characteristic of fibrous proteins?
Which of the following is a characteristic of fibrous proteins?
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What is the main type of structural feature that proteoglycans share?
What is the main type of structural feature that proteoglycans share?
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Which glycosaminoglycans are predominantly found in cartilage proteoglycans?
Which glycosaminoglycans are predominantly found in cartilage proteoglycans?
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What type of bond forms between the xylose and serine in the GAGs-protein linkage?
What type of bond forms between the xylose and serine in the GAGs-protein linkage?
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What is the characteristic shape of a proteoglycan molecule compared to a common object?
What is the characteristic shape of a proteoglycan molecule compared to a common object?
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What stabilizes the association between proteoglycan monomers and hyaluronic acid?
What stabilizes the association between proteoglycan monomers and hyaluronic acid?
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How many GAG chains can be covalently attached to a single core protein in a proteoglycan monomer?
How many GAG chains can be covalently attached to a single core protein in a proteoglycan monomer?
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Which statement is true regarding the formation of proteoglycan aggregates?
Which statement is true regarding the formation of proteoglycan aggregates?
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What distinguishes GAG chains from the core protein in terms of size?
What distinguishes GAG chains from the core protein in terms of size?
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What structural components are Glycosaminoglycans (GAGs) primarily composed of?
What structural components are Glycosaminoglycans (GAGs) primarily composed of?
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How do the negatively charged groups in GAGs affect their behavior in solution?
How do the negatively charged groups in GAGs affect their behavior in solution?
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What role do GAGs play in the extracellular matrix (ECM)?
What role do GAGs play in the extracellular matrix (ECM)?
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Which of the following is commonly associated with GAGs?
Which of the following is commonly associated with GAGs?
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What property of GAGs contributes to their viscous and lubricating nature in mucous secretions?
What property of GAGs contributes to their viscous and lubricating nature in mucous secretions?
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Which bodily tissues are known to contain Glycosaminoglycans?
Which bodily tissues are known to contain Glycosaminoglycans?
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What functional aspect do carboxylic and sulfate groups impart to Glycosaminoglycans?
What functional aspect do carboxylic and sulfate groups impart to Glycosaminoglycans?
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What major percentage of Glycosaminoglycans is composed of carbohydrates?
What major percentage of Glycosaminoglycans is composed of carbohydrates?
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Study Notes
Maroteaux-Lamy Syndrome
- Deficiency in arylsulfatase B leads to the accumulation of dermatan sulfate, causing Maroteaux-Lamy syndrome (MPS VI).
Proteoglycans Overview
- Essential components of extracellular matrix (ECM) and cell surfaces, consisting of a core protein with covalent glycosaminoglycan (GAG) attachments.
- Structure resembles a bottle brush, with GAG chains extending from the core.
Structure of Proteoglycan Monomer
- Comprised of a core protein to which up to 100 GAG chains are covalently linked.
- Each GAG chain can contain up to 200 disaccharide units.
- Main GAGs in cartilage proteoglycans include chondroitin sulfate and keratan sulfate.
- Proteoglycans belong to gene families with shared structural features, such as the aggrecan family.
GAGs-Protein Linkage
- GAGs are covalently bonded to core proteins via trihexosides (galactose-galactose-xylose) connecting to serine residues.
- O-glycosidic bonds form between xylose and serine hydroxyl groups.
Aggregate Formation in Proteoglycans
- Multiple proteoglycan monomers associate with hyaluronic acid forming non-covalent aggregates.
- Ionic interactions stabilize the association, assisted by link proteins.
Glycosaminoglycans (GAGs) Characteristics
- Composed of repeating disaccharide units made of amino sugars and uronic acids.
- Amino sugars may be acetylated or sulfated, contributing to negative charges.
- Negative charges lead to molecular repulsion and water attraction, producing viscous solutions and gel-like matrices.
GAGs Functionality
- Comprise up to 95% carbohydrates, forming the ground substance of ECM.
- Hydrated GAGs support ECM flexibility, interacting with structural and adhesive proteins.
- Serve as molecular sieves, regulating material movement within the ECM.
- Contribute to the viscous properties of mucous secretions, previously referred to as mucopolysaccharides.
Fibrous Proteins Overview
- Have compact structures resulting from diverse protein folding (secondary, tertiary, quaternary).
- Notable examples: collagen and elastin; minor examples include fibronectin and laminin.
Collagen Properties
- Most abundant protein in the human body (25% total protein mass).
- Forms tough fibers resistant to shearing forces, prevalent in bone, tendon, and skin.
- Comprises 28 distinct types, with 90% being types I, II, III, and IV.
- Types I, II, and III are fibrillar; Type IV forms networks resulting in a three-dimensional mesh.
Collagen Structure
- Composed of three helical polypeptide alpha chains in a triple helix configuration.
- Characterized by a repeating glycine-rich sequence (Gly-X-Y), where X is usually proline and Y is predominantly hydroxyproline.
- Proline and hydroxyproline enhance the rigidity of the collagen helix due to their restricted rotation and bulk.
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Description
Explore the role of proteoglycans and their connection to Maroteaux–Lamy syndrome, which arises from a deficiency in arylsulfatase B. This quiz highlights the structure and importance of proteoglycans in the extracellular matrix and cell surfaces, as well as the clinical implications of their dysfunction.
