protein structure and function Flashcards Preview

Botany > protein structure and function > Flashcards

Flashcards in protein structure and function Deck (43)
Loading flashcards...
1

Examples of Silk Proteins

1. Collagen
2. Elastin
3. Keratin
4. Silk Fibroin

2


▪ insoluble, extracellular (found outside the cell)


Collagen

3

▪ very strong due to aldol crosslinks (covalent bond)
▪ found in all animals

Collagen

4

▪ most abundant in the human body

Collagen

5

▪ essential in all connective tissues e.g. cartilage, bone, tendons, ligaments, and skin

Collagen

6

▪ triple helical structure (tropocollagen) stabilized by

aldol crosslinks

7

▪primary structure of collagen

repeating tripeptide (Gly-X-Y) where X is usually Pro and Y is usually hydroxyproline

8

they also exhibit H-bonding because of hydroxyproline

Collagen

9

they are not α-helical; just helical

Collagen

10

– excessive collagen synthesis

Fibrosis

11

▪ overproduction of type 1 collagen in lungs reduces the lung’s ability to expand for air intake and interferes with normal breathing; scarring of lungs

Pulmonary fibrosis

12


▪ excessive deposition in liver leads to scar tissue formation due to overconsumption of alcohol; may lead to cirrhosis

Liver fibrosis

13

caused by insufficient collagen production where skin and tendons are weak and easily stretched producing loose joints and hyperextensive limbs

Ehler’s-Danlos (Rubberman syndrome)

14


▪ type 1 procollagen molecules fail partially or completely to assemble into triple helices and are therefore degraded.
▪ reduced amount of collagen leads to fragile bones; easily fractured

Osteogenesis Imperfecta (Brittle bone syndrome)

15



▪ found predominantly in walls of arteries, lungs, intestines, skins, etc.

Elastin

16

▪ structural proteins that gives elasticity to the body’s tissues and organs

Elastin

17

MW of elastin

72 kDA

18

AAs in elastin

Small nonpolar
A,V, L,G

19

▪WHY hydrophobic elastin molecules “slide and stretch” over one another

to maintain structural integrity and provide recoil

20

▪ elastin protein molecules are crosslinked by WHAT TYPE OF BONDS

covalent bonds

21

tough, fibrous, insoluble protein that makes up the skin, hair and nails

KERATIN

22

also found in claws, hooves, feathers and horns

KERATIN

23

human hair is __% cysteine;

14

24

the more disulfide bridges present, the _ curly

more

25

Soft Keratin –____disulfide bonds
Hard Keratin – ____disulfide bonds

soft - less
hard-more

26

-most abundant protein in vertebrates
-has 3 polypeptide chains wrapped around each other in a ropelike twist or triple helix

collagen

27

collagen fibers are both intra and intermolecularly linked by covalent bonds formed by reactions of ______ residues

lysine and histidine

28

side chains of collagen are on the __ of the triple-helical molecule

surface

29

in collagen, the AA which facilitates formation of the helical conformation of each alpha chain because it causes kinks

Proline

30

in collagen, the AA which fits into the restricted spaces where the 3 chains come together

Glycine

Decks in Botany Class (324):