Glycosaminoglycans and glycoproteins Flashcards by Rebecca Ruthberg

GAGs stand for

glycosaminoglycans

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what are GAGs

modified sugars (glusocamine, iduronic acid, etc). their structure is for their function

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proteoglycan aggregates are present in

cartilage

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GAGs structure describe

hyaluronic acid with core protein with proteoglycan monomer

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synthesis of GAGs come from

intermediates of glycolysis

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glutamine to glutamate is it ender or exerognic

exergonic

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when you are intermediate to polymer you need

high energy bond

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what is the high energy bond used when you are intermediate to polymer

UTP

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all amino sugars stem from

glucosamine-6-P

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glucosamine-6-P originates from

fructose-6-P and glutamine

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normal sugar metabolism supplies all

sugar components

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UDP glucuronate is used how

to make things that are not soluble in water be able to be used in water and be in water.

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what is mediating connection b/w polymer and the protein in carbohydrate chain

xylose, galactose, galactose

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b/w the protein and the sugar there is what bond

O-linked glycosidic bond

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the addition of sugars is via activated

nucleotide donors

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GAGs are located where

extracllular

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to degrade GAGs what needs to appen

they must first be engulfed by invagination of cell membrane, forming vesicle inside of cell

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where are GAGs degraded

lysosomes

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when we age, we start to lose cartilage and when we lost it is because of

degradation of cartilage causes inflammation and causes pain
doctors recommend vitamins: chondroitin sulfate in the hope the chondrocytes will produce more cattilage to replace what is being degraded

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what do doctors recommend to old people in pain b/c they are losing cartilage

taking vitamins to help their body make more cartilage

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what is another name for glucosaminoglycans

mucopolysaccharides

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MPS is the same as

GAGs

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explain hereditary disease of mucopolysaccharides

The mucopolysaccharidoses are hereditary diseases (approximately 1:25,000 live births) caused by a deficiency of any one of the lysosomalhydrolasesnormally involved in the degradation of heparan sulfate and/or dermatan sulfate

They are progressive disorders characterized by lysosomal accumulation of GAG in various tissues, causing a range of symptoms, such as skeletal and ECM deformities, and intellectual disability.

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where do MPS diseases take place

lysosome

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GP stands for

glycoprotein

mostly protein, a little bit carbohydrate

in GPs proteins and oligosaccharides are attached how

covalently

virtually all of our secreted globular proteins are

glycoproteins

what is function of GPs

lots! cell markers, antigenicity, receptors, attachment sites, lubrication of body passages & vasculature, nutrient absorption (eg: Vit B12 – requires intrinsic factor from stomach)

what is linkage of GAGs?

glycosidic linkage | serine linkage

what is linkage of glycoproteins

N-link | O linked

what are the two glycosidic bonds a glycoprotein can have

N or O linked (can also have both)

describe N-linked

glycosidic bond b/w anomeric carbon in carbohydrate and aspragaine

look at pic of glycoprotein linkage

pg 21

synthesis of o linked glycosides is similar to that of

GAGs

draw out the assembly of N linked glycoproteins

pg 23

where is N linked glycoproteins happenign

ER (this is unusual)

mannose has to be phosphorylated to produce

mannose 6 phosphate

when mannose isn't phosphorylated what happens to it

it is secreted

I cell disease is due to absent

lysosomal glycoprotein hydrolases

show the lysosomal hydrolase and he two steps in the mannose phosphorylation pg 24

pg 24

what are classic features of I cell disease

skeletal abnormalities & joint movement; severe psychomotor impairment; death by 8 yrs common

what is on the surface of blood for ABO system

glycoprotein

UDP glucuronate is a product of

UDP glucose

what will UDP glucuronate be used to make

lots of things! especially GAGs (iduronate, UDP-xylose) steroids, drugs, bilirubin proteoglycans

when glucuronate is attached what does it do

negative charge, raises solubility, enhanced water-holding

where is the core protein synthesized

by ribosomes on RER

after the core protein is synthesized in ER, what happens

it is glycosylated by membrane membrane-bound glycosyltransfererases located in the Golgi

defect in sulfation of GAGs result in

disorder: chondrodystrophies (affects proper development and maint. of skeletal system)

when does sulfation of a GAG occur?

after the particular monosaccharide to be sulfated has been incorporated into the growing carbohydrate chain

chondroitin sulfate is a

sulfated GAG

sulfation reaction is catalysed by

sulfotransferases

what is the source of sulfate for sulfating GAGs

PAPs

what does Chondrodystrophies affect

proper development and maint. of skeletal system

hereditary disorder of GAG degradation:

Mucopolysaccharidoses

where is the enzyme deficiency in Mucopolysaccharidoses

deficiency of a lysosomal hydrolase

name three examples of Mucopolysaccharidoses

hunter hurler's sanfilppo

O-linked oligosaccharides can have what structure

linear or branched

draw the A and B blood antigen

pg 26

what forms the H antigen, the substructure of A and B blood groups

fructose linked to galactose

MPS stands for

Mucopolysaccharidosis

what is the most severe of all MPSs

Hurler's

corneal clouding, mental retardation, dwarfing, coronary artery blockage, early death is what disease

Hurlers

where is the specific enzyme defect in Hurler's

Iduronidase

hurler's disease and it's defect in iduronidase ultimately leads to what

accumulation of non-degradable GAGs

where are a lot of GAGs found

in joins

what do GAGs function as in joints

shock absorber | when compressed, water goes out, then water is let back in when compression stops and reforms its shape.

what is the charge of GAGs and how does this affect its relationship with water

It is negative, it attracts water

draw the general linkage b/w core protein and rest of GAG

pg 6

what is a triheoxide

galactose-galactose-xilose

what is biological significance of dermatan sulfate

skin, blood vessels, heart valves

what is the biological significance of chondroitin 4 and 6 sulfates

in cartilage | they bind collagen and hold fibers a tight, strong network

what is the biological significance of keratan sulfates

KS I in cornea | KS II in loose CT

what is the biological significance of heparin

anticoagulant

what is the biological significance of hyaluronic acid

synovial fluid of joints, vitreous humor of eye, umbilical cord, loose CT, cartilage

what is the biological significance of heparan sulfate

extracellular GAG found in basement membrane