Biochem - Collagen and GAGS Flashcards
Turnover time for collagen in anchoring fibers and peridontium?
24 hours
Where can TIV collagen be found?
Basement membrane
T3 collagen increases what?
Flexibility
What types of collagen in gingiva?
1,3,4,5,6
What types of collagen in perio ligament?
1,3,5
What types of collagen in cementum?
1,3,5 (sharpey fibers)
What types of collagen in alveolar bone?
1,3
Hydroxyapatite
Ca5(PO4)3OH
What is known to have a high secretory component?
Odontoblastic processes (tubules)
What is required for a high secretory capacity?
RER, Golgi, and various vesicles
Protein that is similar to collagen in enamel mineralization process?
Amelogenin
Dentin process
RER (collagen is here) -> golgi -> secretory vesicles -> fuse with plasma membrane -> collagen is released -> fibrous network is formed and gets mineralized -> dentin
What is harder, enamel or dentin?
Enamel
T1 collagen AA composition
- 33% glycine
- 15% proline or hydroxyproline
What type of helix is collagen?
- Left handed helix
- 3 AA’s per turn (small diameter)
When 3 collagen chains come together, what do they form?
- Triple helix
- RIGHT handed
Collagen sequence
(Glycine - X - Y)n
*every 3rd residue is glycine
What is usually in the Y position in a collagen sequence?
- HyPro
- HyLys
Polymerized forms of collagen
T1- Fibril
T2- Fibril
T3- Fibril
T4- Sheet-like
Hydroxylation of Pro and Lys in collagen require:
O2
Fe2+
a-ketoglutarate
Vit C (ascorbic acid)
Scurvy is a deficiency in what vitamin?
Vit C
Scurvy can result in:
- reduced collagen stability
- skin legions
- poor wound healing
- breakage of blood vessels
What are propieces and where are they found?
- Extensions (on C and N termini) on collagen polypeptides that are not found in mature collagen
What do C terminal propieces facilitate?
Triple helix formation
What do propieces prevent?
Premature aggregation
What is the purpose of gaps in the arrangement of triple helices?
Serve as a nucleation point for CaPO4 and mineralization of teeth and bone
T4 collagen NC domain purpose
Leads to a mat-like structure (as opposed to bundles)
What does HyPro do in terms of collagen denaturation?
It increases the temp needed to denature collagen from 24 to 39
What does lysine amino oxidase require in order to function?
Copper
What 2 things are needed in the diet for collagen metabolism?
- Copper
- Vitamin C
How can thermal stability be increased?
Through covalent crosslinking of collagen triple helices
Ehler Danlos IV
Premature degradation of T3 collagen (affects elasticity)
Osteogenesis imperfecta type 1
Decreased synthesis of T1 collagen (teeth and bone)
Osteogenesis imperfecta type 2 AND Dentineogenesis imperfecta type 1
Loss of function in triple helix region of T1 collagen (teeth and bone)
Dentineogenesis imperfecta type 2 AND Dentine dysplasia
- DSPP
- Teeth only (no bone involvement)
Definition of carbohydrates
Polyhydroxy aldehydes or keytones
What is the critical role of DPP?
- Binding to the cavities in the collagen fibrils and initiating the mineralization process
- Would have weaker teeth without it
Elastin…
- Lacks any type of structure
- Is cross-linked
- Hydrophobic chains
- When pressure is released, it snaps back on itself due to the hydrophobic interactions
What is a C4 epimer of glucose?
Galactose
What is a C2 epimer of glucose?
Mannose
Glucose structure from C2-C5
down, up, down, up
What happens to a carb when an O-Glycosidic bond is formed?
It becomes non-reducing because it no longer has a free aldehyde and is not in equilibrium with its straight chain form
Humans lack an enzyme capable of hydrolyzing which type of linkages?
Beta 1-4 linkages
What does cellulose pass through the GI tract as?
Fiber (It’s B 1-4 linked)
What do you need to get into the secretory pathway and onto the plasma membrane during protein trafficking?
Into: signal peptide
Onto: stop transfer sequence
N-linked glycosylation:
- Asn-X-Ser or Asn-X-Thr
- 14 residue core oligosaccharide is attached to Asn through an N-glycosidic bond
What is dolichol?
A lipid that provides energy for forming N-glycosidic bonds
What is a complex class?
Defined by sialic acid (nana)
What is a high mannose class?
Defined by persistence of mannose residues
How are core oligosaccharides added?
Cotranslationally
How are core oligosaccharides anchored to the ER membrane?
Linkage with dolichol
Glycosylation occurs through an ordered series of processing reactions that involves what?
Trimming and addition of carbs
Function of glycosylation?
- Protect proteins from degredation
- Acts as a mechanical “stiff arm”
- Mechanical recognition
Failure to breakdown GAGs can lead to…
Muscopolysaccharidoses, buildup in the joints, and many syndromes and diseases
