Elastin, Tissue resilience Flashcards
where is the most elastin? how much?
arteries. ~50%
What elastins half life?
~40-70 years
does tropoelastin have glycosilation?
no
is tropoelasin soluble?
yes. in water <20c.
but elastin isnt
Describe the structure of elastin
repeats of crosslinking domains and hydrophobic domains
Which AA is elasin high in and why?
hydrophobic res - coacervation
Lys - for crosslinking
Which AA is elasin low in? What is the consequence of this?
No met. CnBr can be used to clean it because it doenst get cleaved and everything else does
What does n-mer assembly of elastin look like?
Bootlink n-mer
Which temp range causes coacervation?
35-40c
what is coacervation
Coacervation is an endothermic, entropically-driven process driven by the cooperative interactions of hydrophobic domains following destabilization of the clathrate-like water shielding these regions.
Which res are NOT in the hydrophobic regions?
No
Met, Tyr, His, Lys
What secondary structure is the hydrophobic region
beta turns
What secondary structure is the crosslinking region
alpha helices
What bonds is between the beta turns in hydrophic repeats?
h-bond
What sticks out from the top and bottom of the beta turns?
large hydrophobic side chains
Which res are in the hydrophobic regions?
hydrophobic
gly, val, ala, pro,
cross describe the cross sectional view of the cross linking domains
high in lys and ala
What arrangement of lys and ala? why?
2,3-ala
lysine to be arranged near one another for crosslinking
What is between lysine crosslinks? how many lysines?
desmosines
4
What enzyme needed for lysine crosslinking? what kind of bond does it creatE?
lysyl oxidase.
covalent
What happens to the beta sheets in the stretched and relaxed position of elastin?
relaxed - hydrophobic side chains gather up to avoid water
what is elastin in animals?
resilin
Why is entropy decreased in stretched state of elastin?
hydrophobic side chains revealed to water
what happens to entropy in relaxed state?
increases because hydrophobic side chains join together freeing the water molecules from solvation shell
tropoelastin coacervation is ______ driven and ____thermic
entropy
endo
Why doesn’t tropoelastin polymerize inside the cells?
Bound to EBP (elastin binding protein) complex in vesicle.
in extracellular env, galactose sugar binds to EBP and releases elastin. galactose sugar found in fibrillin. This then allows the coacervation
What would happen to elastin without galactose sugar or fibrillin?
it would never release in the extracellular space
Name a pattern of AA that would bind to peripheral protein on the EBP
VGVAPG
What is required for the galactose sugars to be available from fibrillins? Why?
neuraminidase
It removes the sialic acid that is bound to the galactose sugar. Until the sialic acid is unbound, the galactose cant bind to tropoelastin
What kind of staining used for elastins?
Hart’s stain
What kind of stain for aSMA?
immunostain
What kind of stain for sialomucins?
alcian blue stain
What can be seen in neu -/- for elastins?
Aorta and smooth muscle cells have fewer and more sparse unorganized lamillae
What is usually bound to the galactose on fibrillin?
sialic acid
Which is older? Fibrillin or elastins?
Fibrillin
How can we see if the localization of elastin and fibrillin-1?
immunostaining
How many AA in fibrillin crosslinking and what are the AAs?
glutamine and lysine
What type of crosslinking does fibrillin have?
transglutaminase crosslinking
Which structure requires Ca2+? elastin or fibrillin?
fibrillin microfibrils
is microfibrillar-associated protein 4 (MFAP-4) necessary for elastogenesis? why?
Yes.
allows microfibril formation of fibrillin-1
without which crosslinking between elastin and fibrillin doesnt work
What is required for fibrillin microfibril formation?
microfibrillar-associated protein 4 (MFAP-4)
Which protein is needed for avb3 integrin recognition? What type of motif would this protein have?
MAGP-2
RGD motif
Which protein increases microfibril stability?
MAGP-1
Fibrillin-1 mutation would cause?
loose joints
aneurysms
Fibrillin-2 mutation would cause?
spider finger
marfan like
tropoelastin mutation would cause?
narrowing of arterial lumen
congenital redundant skin
Cutis laxa is caused by what? what is the inheritance type of this disease?
tropoelastin mutation
elastin exon numbers for hydrophobic domains are?
elastin exon numbers for crosslinking domains are?
20, 24^4
21,23
mimetic peptide elastin exon numbers for hydrophobic domains are?
- 24^2
Can elastin self assemble?
Yes
Coacervation transition temp changes how with number of hydrophobic domains and ionic strength?
# of hydrophobic domains (up) > lower transition temp. ionic strength (up) > lower transition temp.
What would happen with fewer hydrophobic domains?
higher temp required for coacervation.
so chronic wounds and skin grafts
What would happen with lower ionic strength?
higher temp required for coacervation.
so chronic wounds and skin grafts
What is a good tissue engineering solution for vascular grafting? Why?
elastin like surface
allows binding of smooth muscle cells and epithelial cells. This was possible by VGVAPG sequencing binding to the laminin.
Also, it was shown to inhibit platelete adhsion and fibrinogen surface absorption
Name another use of engineered tropoelastin other than vascual grafts
Recombinant tropoelastin coated stents to prevent thrombosis. like a net that holds the vessels open
strongest elastic protein known in nature? Where is it located? What can you do with it?
resilin
in fleas. between the wing and the dorsoventral muscles
can jump 150x height
What AA is abundant in hydrophobic regions in resilin?
Glycine
What are helix break AAs? What do they do?
Glycine and Proline
They break regular helices and create turn conformations
What AA forms the crosslinking in resilin?
Di/tri-tyrosine
What is spider silk made of? What AA is abundant in it?
fibroin - made of spidroin
glycine and alanine
What is the structure of spidroin and what AA is in these structures?
beta sheets - Gly/Ala rich
crstaline Ala repeats in between
