lecture 1 part b Flashcards
1
Q
what mucin genes are secreted in the stomach?
A
- 5a,c and 6
2
Q
what are mucins secreted in small intestine for?
A
- absorption
3
Q
what are mucins secreted in stomach for?
A
- doesnt want absorption
- only absorbs aspirin (becomes uncharged in acid so can be absorbed)
4
Q
what does the N terminal allow?
A
- globular
- polymerisation
- form large complexes
5
Q
what are VNTRs?
A
- variable number tandem repeats
- sequence of a.acids that repeats multiple times
- contains serine, threonine and proline (STP region)
6
Q
what is the structure of serine and threonine?
A
- have OH group
- can attach carbohydrates
- highly glycosylated
7
Q
what are regions between molecules susceptible to?
A
- proteolytic enzymes
8
Q
why does the stomach need secretion of acid?
A
- to balance with the erosion
9
Q
why do the mucins need to be polymerised?
A
- to form gel
- can then be degraded by pepsin
10
Q
what is pepsin?
A
- stomach enzyme
- used for food digestion
11
Q
where should pepsin have no activity?
A
- at surface
- not correct pH
12
Q
which pepsin is the most negatively charged?
A
- pepsin 1
13
Q
which pepsin is the least negatively charged?
A
- pepsin 5
14
Q
what can pepsin isoenzymes be separated by?
A
- agar gel electrophoresis at ph5
- anion exchange
15
Q
what is the mechanism of activation of pepsin?
A
- lid over active site formed by N terminal of molecule
- 2 points of cleavage (16&17, 44&45)
- hydrophobic amino acids present at cleavage points
- ## pepsin cleaves between the 2 hydrophobic amino acids