Collagen and Elastin

Question 1

What 4 components make up collagen?

Answer 1

Glycine
Proline
Hydroxyproline
Hydroxylysine

Question 2

What enzymes are responsible for the hydrozylation of lysine and proline and what is their cofactor?

Answer 2

Lysyl hydroxylase and Proyl hydroxylase

Cofactors is Vitamin C (ascorbate)

Question 3

Osteogenesis imperfecta, what are the symptooms, what is the cause?

Answer 3

AKA Brittle Bone Syndrome

Caused by gly being replace by another amino acid in collagen chains, this causes poor collagen packing and unstable collagen.

Two Types: Type 1 sees fractures are newborns, blue sclera, hearing loss and dental imperfections. Type 2 fetus would die inutero of pulmonary hypoplasia

Question 4

What is stickler syndrome?

Answer 4

Stickler syndrome is a group of hereditary conditions caused by mutations in collagen genes

You see: a distinctive facial appearance, myopia, hearing loss, joint problems, poor bone formation and flattened face/cleft palate

Question 5

How is collagen synthesized?

Answer 5

Prepro-alpha chains are synthesized in the rER

• guided in lumen by N signal seq
• signal seq is cleaved -> pro-alpha chain /

3 alpha chains made of glycine, proline, hydroxlproline, and hydroylysine forms a tropocollagen

• Lysine and prolines are hydroxylated (w/VitC, Fe2+ and O)
• hydroxylysine residues are glycosylated

(Tro)procollagen is secreted and in the EC matrix they are assembled into collagen fibrils where lysyl oxidase performs crosslinking (cofactor copper)

Question 6

What is scurvy?

Answer 6

Caused by vitamin C deficiency

This is becauses hydroylation isnt happening without it’s cofactor causing pooor assembly and crosslinking of collagen

Blood vessels are weak, they bleed for longer and woulnds heal slowly and poorly

Question 7

Ehlers Danlos Syndrome

Answer 7

Caused by either mutations in collagen genes (1,3 or 5) or mutations or defective collagen processing enzymes

Characteristics - weka bones and muscles, hyperextensible skin, hypermobile joints and skin and easy bruising

Question 8

What is Menkes disease?

Answer 8

Caused by impaired copper and absorption and transport. Copper deficiency decrease lysyl oxidase activity causing poor collagen crosslinking

Characteristics - hypotonia, kinky hair, weak bones, deterioration of the nervous system giving developmental delay and intellectual disability.

Question 9

What is osteolathrrism and it’s cause?

Answer 9

Caused by toxic osteolathrogens, these inhibits lysyl oxidase meaning there’s no crosslinking between collagen.

-> south asia where grass pea is consumed

Characterized by soft deformed bones and weak muscles

Question 10

What are the components of elastin?

Answer 10

Proline, lysine, and small hydroyproline