Shared Flashcard Set

Details

Biochemistry-Rosa Huang
HSF-1 Biochem
28
Biochemistry
Professional
01/21/2012

Additional Biochemistry Flashcards

 


 

Cards

Term
Collagen I-IV
Definition
I- bone, skin, tendon, cornea
II-cartilage, intervertebral disc, vitreous body
III- fetal skin, cardiovascular system
IV-basement membrane, lens capsule
Term
amino acid composition in collagen
Definition
gly, pro, hyp,hyl

recurring sequence: gly-pro-hyp
Term
Explain how Hyp is formed
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.
Term
Why does the reaction catalyzed by prolyl hydroxylase need ascorbate. What is ascorbate.
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.
Term
function of hyp and hyl
Definition
they allow the triple helix formation that helps make collagen so strong.
Term
What are the enzymes that are necessary for glycosyation of hyl?
Definition
galactosyl transferase and glucosyl transferase
Term
what disease is caused by hypovitaminosis C
Definition
scurvy.
Term
dimensions of tropocollagen
Definition
d=3.12
n=3
p=9.36
Term
what direction is the tropocollagen helix
Definition
left handed
Term
is tropocollagen stable or not stable. Why
Definition
not stable. steric repulsion of pyrrolidone rings or pro residues. There are no intra-chain hydrogen bonds.
Term
what hand is mature collagen
Definition
right handed
Term
dimensions of mature collagen
Definition
d=2.9
n=3.3
p=9.5
Term
is mature collagen stable or not. Why
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
Term
What is the precursor for tropocollagen
Definition
procollagen
Term
how is procollagen converted to tropocollagen. Describe the pieces that are lost
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
Term
What disease results from deficient procollagen n-protease? what are the signs
Definition
ehlers-danlos syndrom type VII. hypermobile joints, stretchable skin, short stature.
Term
Describe the arrangement of collagen fribrils
Definition
tropocollagen associates spontaneously into quarter staggered layers forming the fibrils.
Term
how is mature collagen derived from collagen fibrils. What are the parts that make up the mature collagen's stability
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.
Term
What is lathyrism
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)
Term
What are the steps for the formation of mature collagen starting at the beginning. Note the locations of each step
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!
Term
What is lobstein syndrome
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 .
Term
What are proteoglycans made up of?
Definition
polysaccharide/protein. Mostly polysaccharide(95%)
Term
What makes up the polysaccharide component of proteoglycans?
Definition
GAGs (glycosaminoglycans or mucopolysaccharides composed of disaccharide repeating units like hexosamine or uronic acid
Term
What are the 6 classes of glycosaminoglycans and what does each of them consist of?
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
Term
Whats the difference between heparin and heparan
Definition
heparan has more N-acetate(less N-sulfate)
less O-sulfation
some of the glucuronic acids are replaced w/ iduronic acids
Term
what is the feature of all mucopolysaccharides that is defective in mucopolysaccharidoses
Definition
lysosomal hydrolase.
Term
What are morphologic abnormalities of many parts of the skeleton
Definition
dysostosis multiplex.
Term
What are the 5 mucopolysaccharidoses that we discussed
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
Supporting users have an ad free experience!