L18 Flashcards
1
Q
____mg/mL protein
A
400mg/mL protein
2
Q
Avg protein
- ___nm diameter
- ____ nm space btwn
A
Avg protein
- 6 nm diameter
- 7 nm space btwn
3
Q
The different paths to the folded state is often show on a ___ shaped plot
A
funnel
4
Q
Obstacles to reaching the native state
A
- Incorrect disulfide bond formation
- Incorrect Xaa-Proline isomer (cis/trans)
- Aggregation thru exposed hydrophobic surfaces during folding steps
5
Q
Advantages of ribonuclease A
A
- Free
- Lots available
- Pure
- Enzyme activity assay
- Small and soluble
- Helices, sheets, 4 disulphides
6
Q
Denature/renature experimental steps
A
- Unfold ribonuclease A; 8M urea and BME
- > Inactive enzyme - Dialyze ribonuclease A to remove denaturants
- > inactive enzyme - Added trace amts of BME to get correct disulfides
- > active enzyme
7
Q
Role of chaperones/chaperonins
A
- Neither can actively fold proteins
- Chaperones and chaperonins may be constitutively expressed (always present) or stress-regulated (so called heat shock proteins) by heat, cold, starvation, poisoning, and other forms of stress can also activate their synthesis
8
Q
Fxn of molecular chaperones
A
Prevent misfolding and aggregation, but they cannot unfold misfolded proteins.
9
Q
Prokaryotic Hsp70s are often called
A
DnaK
10
Q
What are the 2 domains of chaperone DnaK/Hsp70?
A
- ATPase domain
2. Peptide binding domain
11
Q
2 fxns of Hsp70/chaperone DnaK
A
- Bind to newly synthesized proteins as they come from the ribosomes to prevent them from misfolding.
- Import of nascent proteins into organelles
12
Q
Describe Hsp90
A
- Homodimer
- ATPase
- Acts together w/Hsp70 and several other chaperone proteins
13
Q
What are 4 inhibitors of Hsp90 with antitumor effect?
A
- Geldanamycin
- Celastrol
- Radicicol
- Gedunin
14
Q
Describe prefoldin
A
- 6 legged octopus
- coiled coil
- 2 top structures are beta barrel
15
Q
Fxn of chaperonins
A
Actively unfold misfolded proteins, using energy from ATP-hydrolysis
