9 Protein Folding Flashcards Preview

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Flashcards in 9 Protein Folding Deck (24):
1

what is the general process by which insulin is prepared?

proteolysis

2

what is the difference between preproinsuin, proinsulin, and insulin? and where is each found?

-prepro has a signal sequence, an A and B chain, and a C peptide. found inside the cell in a reduced form
-pro insulin is created by cleaving the signal sequence from preproinsulin. Found in the ER in an exidized state
-insulin is made by cleaving the C peptide from proinsulin

3

is preproinsulin oxidized or reduced?

-reduced

4

is proinsulin oxidized or reduced?

oxidized

5

is insulin oxidized or reduced?

oxidized

6

when oxidation occurs, and preproinsulin is turned into proinsulin, what does this allow to happen?

the formation of disulfide bonds between the A and B chains, allowing for much greater stability

7

the cytoplasm of the cell is usually an oxidizing or reducing environment?

reducing (this is why preproinsulin is reduced and disulfide bonds are not present (Sulfurs bound to hydrogen)

8

proteins fold to maxmize what>

-weak, noncovalent forces

9

bone skin and tendon are made up of what type of collagen?

Collagen type 1

10

reticulin fibers are made up of what type of collagen?

collagen type 3

11

what are the two standard repeat sequences found in collagen?

Gly-Pro-random
Gy-pro-hydroxyproline

12

other than proline, what else is hydroxylated in collagen?

lysine

13

what does improper hydroxylation of collagen cause and what causes this?

-scurvy (lack of hydroxylation)
-vitamin C deficiency

14

what end of collagen begins to fold first? the formation of what begins this process?

-c terminus (in most proteins it is the N, which is synthesized first)
-disulfide bonds, intra and inter chain

15

what causes the elongated helical structure found in collagen?

steric hinderance between prolinesq

16

what allows collagen chains to pack so tightly together?

so many glycine residues

17

the conversion of procollagen to tropocollagen takes place where?

ECM

18

what do tropocollagen spontaneously assemble into and how does this happen?

-fibrils
-has a sticky end that attaches to the next collagen

19

what causes osteogenesis imperfecta?

-a glycine in the collagen triple helix region being mutated to a cystein

20

why is osteogenesis a dominant mutation?

-because it is a protein with multiple subunits
-all chains have to be correct for the protein to function

21

explain the mechanism of callagen cross linking

the enzyme lysyl oxidase crosslinks lysine or hydroxylysine to produce allysine

22

what is the cause of ehlers-danlos syndrome?

caused by either a mutation in a collagen processing gene (heterozygosity ok - recessive) or in the collagen gene itself (heterozygosity not ok - dominant)

23

mad cow, srapie, creutzfield jabos, and kuru are all forms of what?

prion diseases

24

what are two ways of acquiring a prion disease?

inherit or acquire a missense mutation (CJD)
-coming into contact with the bad form of the protein (new variant CJD)