ECM Flashcards
What are the 3 major AA types in collagen?
- Glycine (1/3)
- Proline (1/4)
- Lysine
*Pro and Lys are very often hydroxylated
What is a very common AA sequence?
Gly-X-Y
X is usually Pro
Y is usually hydroxyPro
What is the secondary/tertiary structure of collagen?
Type II trans helix (2.8 angstrom rise per AA along the fiber axis).
What is the quaternary structure of collagen? What is it called?
R handed triple helix
Each chain (of the 3) is an Alpha chain, called Tropocollagen as a whole
What causes osteogenesis imperfecta?
Replacement of glycine with a bulkier AA prevents tight binding of triple helix.
Why are alpha chain-encoding genes so much longer than the final polypeptide?
N-terminal extension and C-terminal extension
Where does hydroxylation of proline and lysine occur?
ER
How is proline hydroxylated and what is an important co-factor?
Prolyl hydroxylase hydroxylates C$ using ascorbate as a co-factor.
What disease occurs when ascorbate is missing from the diet?
Scurvy: skin lesions, fragile blood vessels, poor wound healing.
Why is hydroxylation important?
It is required for cross-linking of collagen molecules.
How is lysine hydroxylated? Does it require a cofactor?
Lysyl hydroxylase. Yes, also requires ascorbate
Which common collagen AA can also be glycosylated?
(Hydroxy)Lysine
How does hydroxyproline affect Tm?
Increases it
How is pro-collagen converted into tropocollagen and where?
N and C terminal peptidases in the extracellular space.
What creates the striated appearance of collagen?
asymmetric 1/4 stagger
