Elastin, Tissue resilience

Question 1

where is the most elastin? how much?

Answer 1

arteries. ~50%

Question 2

What elastins half life?

Answer 2

~40-70 years

Question 3

does tropoelastin have glycosilation?

Answer 3

no

Question 4

is tropoelasin soluble?

Answer 4

yes. in water <20c.

but elastin isnt

Question 5

Describe the structure of elastin

Answer 5

repeats of crosslinking domains and hydrophobic domains

Question 6

Which AA is elasin high in and why?

Answer 6

hydrophobic res - coacervation

Lys - for crosslinking

Question 7

Which AA is elasin low in? What is the consequence of this?

Answer 7

No met. CnBr can be used to clean it because it doenst get cleaved and everything else does

Question 8

What does n-mer assembly of elastin look like?

Answer 8

Bootlink n-mer

Question 9

Which temp range causes coacervation?

Answer 9

35-40c

Question 10

what is coacervation

Answer 10

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.

Question 11

Which res are NOT in the hydrophobic regions?

Answer 11

No

Met, Tyr, His, Lys

Question 12

What secondary structure is the hydrophobic region

Answer 12

beta turns

Question 13

What secondary structure is the crosslinking region

Answer 13

alpha helices

Question 14

What bonds is between the beta turns in hydrophic repeats?

Answer 14

h-bond

Question 15

What sticks out from the top and bottom of the beta turns?

Answer 15

large hydrophobic side chains

Question 16

Which res are in the hydrophobic regions?

Answer 16

hydrophobic

gly, val, ala, pro,

Question 17

cross describe the cross sectional view of the cross linking domains

Answer 17

high in lys and ala

Question 18

What arrangement of lys and ala? why?

Answer 18

2,3-ala

lysine to be arranged near one another for crosslinking

Question 19

What is between lysine crosslinks? how many lysines?

Answer 19

desmosines

4

Question 20

What enzyme needed for lysine crosslinking? what kind of bond does it creatE?

Answer 20

lysyl oxidase.

covalent

Question 21

What happens to the beta sheets in the stretched and relaxed position of elastin?

Answer 21

relaxed - hydrophobic side chains gather up to avoid water

Question 22

what is elastin in animals?

Answer 22

resilin

Question 23

Why is entropy decreased in stretched state of elastin?

Answer 23

hydrophobic side chains revealed to water

Question 24

what happens to entropy in relaxed state?

Answer 24

increases because hydrophobic side chains join together freeing the water molecules from solvation shell

Question 25

tropoelastin coacervation is ______ driven and ____thermic

Answer 25

entropy | endo

Question 26

Why doesn't tropoelastin polymerize inside the cells?

Answer 26

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

Question 27

What would happen to elastin without galactose sugar or fibrillin?

Answer 27

it would never release in the extracellular space

Question 28

Name a pattern of AA that would bind to peripheral protein on the EBP

Answer 28

VGVAPG

Question 29

What is required for the galactose sugars to be available from fibrillins? Why?

Answer 29

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

Question 30

What kind of staining used for elastins?

Answer 30

Hart's stain

Question 31

What kind of stain for aSMA?

Answer 31

immunostain

Question 32

What kind of stain for sialomucins?

Answer 32

alcian blue stain

Question 33

What can be seen in neu -/- for elastins?

Answer 33

Aorta and smooth muscle cells have fewer and more sparse unorganized lamillae

Question 34

What is usually bound to the galactose on fibrillin?

Answer 34

sialic acid

Question 35

Which is older? Fibrillin or elastins?

Answer 35

Fibrillin

Question 36

How can we see if the localization of elastin and fibrillin-1?

Answer 36

immunostaining

Question 37

How many AA in fibrillin crosslinking and what are the AAs?

Answer 37

glutamine and lysine

Question 38

What type of crosslinking does fibrillin have?

Answer 38

transglutaminase crosslinking

Question 39

Which structure requires Ca2+? elastin or fibrillin?

Answer 39

fibrillin microfibrils

Question 40

is microfibrillar-associated protein 4 (MFAP-4) necessary for elastogenesis? why?

Answer 40

Yes. allows microfibril formation of fibrillin-1 without which crosslinking between elastin and fibrillin doesnt work

Question 41

What is required for fibrillin microfibril formation?

Answer 41

microfibrillar-associated protein 4 (MFAP-4)

Question 42

Which protein is needed for avb3 integrin recognition? What type of motif would this protein have?

Answer 42

MAGP-2 | RGD motif

Question 43

Which protein increases microfibril stability?

Answer 43

MAGP-1

Question 44

Fibrillin-1 mutation would cause?

Answer 44

loose joints | aneurysms

Question 45

Fibrillin-2 mutation would cause?

Answer 45

spider finger | marfan like

Question 46

tropoelastin mutation would cause?

Answer 46

narrowing of arterial lumen | congenital redundant skin

Question 47

Cutis laxa is caused by what? what is the inheritance type of this disease?

Answer 47

tropoelastin mutation

Question 48

elastin exon numbers for hydrophobic domains are? | elastin exon numbers for crosslinking domains are?

Answer 48

20, 24^4 | 21,23

Question 49

mimetic peptide elastin exon numbers for hydrophobic domains are?

Answer 49

20. 24^2

Question 50

Can elastin self assemble?

Answer 50

Yes

Question 51

Coacervation transition temp changes how with number of hydrophobic domains and ionic strength?

Answer 51

``` # of hydrophobic domains (up) > lower transition temp. ionic strength (up) > lower transition temp. ```

Question 52

What would happen with fewer hydrophobic domains?

Answer 52

higher temp required for coacervation. | so chronic wounds and skin grafts

Question 53

What would happen with lower ionic strength?

Answer 53

higher temp required for coacervation. | so chronic wounds and skin grafts

Question 54

What is a good tissue engineering solution for vascular grafting? Why?

Answer 54

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

Question 55

Name another use of engineered tropoelastin other than vascual grafts

Answer 55

Recombinant tropoelastin coated stents to prevent thrombosis. like a net that holds the vessels open

Question 56

strongest elastic protein known in nature? Where is it located? What can you do with it?

Answer 56

resilin in fleas. between the wing and the dorsoventral muscles can jump 150x height

Question 57

What AA is abundant in hydrophobic regions in resilin?

Answer 57

Glycine

Question 58

What are helix break AAs? What do they do?

Answer 58

Glycine and Proline | They break regular helices and create turn conformations

Question 59

What AA forms the crosslinking in resilin?

Answer 59

Di/tri-tyrosine

Question 60

What is spider silk made of? What AA is abundant in it?

Answer 60

fibroin - made of spidroin | glycine and alanine

Question 61

What is the structure of spidroin and what AA is in these structures?

Answer 61

beta sheets - Gly/Ala rich | crstaline Ala repeats in between