Glycosaminoglycans And Glycoproteins Flashcards Preview

Exam 2 > Glycosaminoglycans And Glycoproteins > Flashcards

Flashcards in Glycosaminoglycans And Glycoproteins Deck (39):
1

Basic Description of GAGs

Heteropolysaccharides made up of repeating disaccharide units

2

relationship between glycosaminoglycan structure and function

The strong negative charges (-Coo- and -Oso3-) cause the molecule to fan outwards and repel adjacent molecules

3

GAG water binding

The negative charges allow the molecule to bind water, leading to each molecule being surrounded by a hydrated shell that gives them compressibility and the ability to spring back to their original shape (resilience).

4

What accounts for the resilience of synovial fluid and vitreous humor?

Reversible compressibility of the water shell around GAG molecules

5

What is the repeating subunit that makes up all GAGs?

Acidic sugar-amino sugar

6

What are the possible amino sugars in GAGs?

D-glucosamine and D-galactosamine

7

What are the acidic sugars that make up GAGs?

D-glucuronic acid or the C-5 epimer L-iduronic acid

8

What is the exception to the acidic sugar rule?

Keratin sulfate where galactose is present instead of an acid sugar

9

Hyaluron

Found in the synovial fluid, vitreous humor, and ECM of loose connective tissue. Large polymers are shock absorbing. Only GAG that doesn't contain sulfate and only GAG that doesn't covalent lay attach to proteins in proteoglycans

10

Chondroitin Sulfate

found in the cartilage,bone, heart valves. Most abundant GAG.

11

Keratan Sulfate

Found frequently with other GAGs. Found in the cornea, bone, and cartilage with chondroitin sulfates

12

Dermatan Sulfates

Skin, blood vessels, and heart valves

13

Heparin

Only intracellular GAG. Component of intracellular granules of mast cells lining the arteries of the lungs, liver, and skin. More Sulfates than heparan

14

Heparan Sulfate

Makes up basement membranes, components of cell surfaces. More acetylated glucosamine than heparin

15

What is hylauronic acid attached to?

Just a sugar, not a protein like all other GAGs

16

The proteoglycan in cartilage is made up of...

Chondroitin sulfate and keratin sulfate attached to a protein core

17

What links carbohydrates and proteins in proteoglycans?

A serine attaches a linking sugar of Gal-Gal-Xyl (tri-hexoside) to the protein core

18

Where are GAGs synthesized?

In the ER and then modified in the Golgi (where acid/amino sugar glycosylation occurs)

19

Glycosyl Transferases

Enzymes that catalyze the elongation of polysaccharide chains by alternate placement of their UDP derivatives

20

Addition of sulfate groups to the proteoglycan:

PAPS donates a sulfate(in the Golgi). Requires sulfotransferase.

21

role of heparin

Prevents coagulation of blood (inhibits blood clotting)

22

Tissue Factor Pathway Inhibitor

TFPI (anti-thrombin III). Mainly supplied by endothelial cells. It is an inhibitor that comes into action when limited quantities of factor Xa are generated. TFPI binds to factor Xa and then to tissue factor VIIa forming an inactive quaternary complex. Heparin induces the release of TFPI.

23

Warfarin

Anticoagulant. Synthetic analog of VitK. Acts slower than heparin so it is administered after

24

What are the major roles of glycoproteins?

Cell surface receptors. (G-proteins), blood type determinant, in collagen, and serve as a protective barrier, and make up intracellular/lysosomal enzymes.

25

What is a glycoprotein?

Protein with attached oligosaccharide.

26

What do extracellular matrix glycoproteins do?

Act as protective biological lubricants

27

What determines the blood type?

Combination of sugars on the glycoproteins

28

Mucin

Large glycoproteins with negatively charged sialic acid, NANA.They occupy a large space and trap water,serving as a protective barrier.

29

O-glycosidic Link

Oligosaccharide attached to the OH group on Serine or Threonine

30

N-glycosidic Link

Oligosaccharide attached to the amide group of asparagine

31

What links the oligosaccharides to the hydroxyl groups?

N-acetylgalactosamine

32

What are the two types of N-linked oligosaccharides?

Complex (diverse group of additional sugars) and high mannose (primarily mannose)

33

What is the charge of an oligosaccharide when NANa is present?

Negative

34

Synthesis of O-linked glycosides

Protein is synthesized in rER and then extruded into lumen of ER. Glycosylation occurs in the Golgi through specific glycosyltransferases that add sugars sequentially.

35

Degradation of GAGs

GAGs, glycoproteins, and glycolipids occurs in lysosomes following their endocytosis

36

Mucoploysaccharidosis

Inability to degrade with GAGs or glycoproteins

37

Sphingolipidosis

Inability to degrade sphingolipids

38

I-Cell disease

Rare syndrome in which hydrolytic enzymes normal found in lysosomes are absent, lack the ability to phosphorylase mannose residues. Usually caused by an issue with protein targeting.

39

Enzymes destined for lysosomes

Usually bound my Mannose-6-phosphate which target the enzymes to facilitate their translocation to lysosomes. Typically hydrolytic enzymes (proteases, lipases, etc..)