Term
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Definition
I- bone, skin, tendon, cornea
II-cartilage, intervertebral disc, vitreous body
III- fetal skin, cardiovascular system
IV-basement membrane, lens capsule |
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Term
| amino acid composition in collagen |
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Definition
gly, pro, hyp,hyl
recurring sequence: gly-pro-hyp |
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Term
| Explain how Hyp is formed |
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Definition
| Hyp stands for hydroxyproline and is formed by an enzymatic rxn that is catalyzed by prolyl hydroxylase. the prolyl residue must be on the amino side of a glycyl residue to undergo the 4-hydroxylation. |
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Term
| Why does the reaction catalyzed by prolyl hydroxylase need ascorbate. What is ascorbate. |
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Definition
| Ascorbate is vit C and it is needed to reduce Fe3 back to Fe2. Fe2(ferrous) iron is necessary to do the hydroxylation reaction to make hyp/hyl. It must be regenerated to make collagen. |
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Term
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Definition
| they allow the triple helix formation that helps make collagen so strong. |
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Term
| What are the enzymes that are necessary for glycosyation of hyl? |
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Definition
| galactosyl transferase and glucosyl transferase |
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Term
| what disease is caused by hypovitaminosis C |
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Definition
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Term
| dimensions of tropocollagen |
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Definition
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Term
| what direction is the tropocollagen helix |
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Definition
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Term
| is tropocollagen stable or not stable. Why |
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Definition
| not stable. steric repulsion of pyrrolidone rings or pro residues. There are no intra-chain hydrogen bonds. |
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Term
| what hand is mature collagen |
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Definition
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Term
| dimensions of mature collagen |
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Definition
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Term
| is mature collagen stable or not. Why |
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Definition
yes it is stable.
because of the transverse inter-strand hydrogen bonds between the backbone amino groups of gly and the backbone carbonyl groups.
hydrogen bonds between hyp and H2O(this raises the melting temp from 24-->58 |
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Term
| What is the precursor for tropocollagen |
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Definition
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Term
| how is procollagen converted to tropocollagen. Describe the pieces that are lost |
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Definition
proteases cut off the c and n terminal peptides. (amounts to 45 kD).
c terminal has intra and interchain disulfide bonds as well as mannose-rich oligosaccharide
n terminal has intra chain disulfide bonds
This modification occurs extracellularly |
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Term
| What disease results from deficient procollagen n-protease? what are the signs |
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Definition
| ehlers-danlos syndrom type VII. hypermobile joints, stretchable skin, short stature. |
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Term
| Describe the arrangement of collagen fribrils |
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Definition
| tropocollagen associates spontaneously into quarter staggered layers forming the fibrils. |
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Term
| how is mature collagen derived from collagen fibrils. What are the parts that make up the mature collagen's stability |
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Definition
cross-links form between the fibrils which makes mature collagen stable.
aldol cross link between 2 aldehydes (lysyl oxidase-Cu/B6 dependent) oxidative deamination.
schiff base and lysinonorleucine cross-links
lysine and allysine form a schiff base and if you add in an H you get lysinonorleucine cross linkage. |
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Term
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Definition
| extremely fragile collagen caused by the ingestion of this sweet pear that contains a toxic agent called beta-aminopropionitrile that inhibits lysyl oxidase(no aldol cross-linkage--> no mature collagen) |
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Term
| What are the steps for the formation of mature collagen starting at the beginning. Note the locations of each step |
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Definition
transcription in the nucleus
polypeptide synthesis in the cytoplasm on ER
hydroxylation/glycosylation on ER
proallagen formation on ER
secretion by the golgi
tropocollagen formation in the ECM
collagen fibril formation in the ECM
formation of cross-links in the ECM
Yay for mature collagen! |
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Term
| What is lobstein syndrome |
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Definition
| osteogenesis imperfecta/ brittle bone disease. Comes from abnormalities in the collagen molecule that forms the bone matrix. Collagen type I forms the bone collagen. There are mutations in the structure genes for the constituent peptides of collagen . |
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Term
| What are proteoglycans made up of? |
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Definition
| polysaccharide/protein. Mostly polysaccharide(95%) |
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Term
| What makes up the polysaccharide component of proteoglycans? |
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Definition
| GAGs (glycosaminoglycans or mucopolysaccharides composed of disaccharide repeating units like hexosamine or uronic acid |
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Term
| What are the 6 classes of glycosaminoglycans and what does each of them consist of? |
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Definition
Hyaluronic acid consists of glcUA, and glcNAc
chondroitin sulfates consist of glc UA and galNAc(6S or 4S)
dermatan sulfate consists of IdUA, GalNAc-4S
keratan sulfate consists of Gal and GlcNAc-6S
Heparin consists of glcUA-2S and glcNS-6S
Heparan consists of glcUA-2S and glcNS-6S |
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Term
| Whats the difference between heparin and heparan |
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Definition
heparan has more N-acetate(less N-sulfate)
less O-sulfation
some of the glucuronic acids are replaced w/ iduronic acids |
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Term
| what is the feature of all mucopolysaccharides that is defective in mucopolysaccharidoses |
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Definition
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Term
| What are morphologic abnormalities of many parts of the skeleton |
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Definition
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Term
| What are the 5 mucopolysaccharidoses that we discussed |
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Definition
Hurler-alpha-L-iduronidase
Scheie-alpha-L-iduronidase
Hurler-Scheie-alpha-L-iduronidase
Hunter-iduronate sulfatase
All of these ^ have urinary GAG excretion of HS and DS
Safilippo syndrome A-form- Heparan N-sulfatase
Urinary GAG excretion ONLY HS |
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