Amino acids, peptides, proteins IV

Question 1

What does protein need to refold?

Answer 1

Just the primary AA structure

Question 2

2 major classes of chaperone proteins?

Answer 2

Hsp70

GroEL

Question 3

Hsp70

Answer 3

Induced by heat. Binds to hydrophobic areas to prevent aggregation, gives proteins another chance to refold

Question 4

GroEL

Answer 4

7 diff subunits in eukaryotes. Binds hydrophobic surface of unfolded protein and puts it in its cavity so it can refold properly.
More generic.
Not heat-induced.

Question 5

what else might a protein need for folding?

Answer 5

Sometimes, proteins require disulfide isomerase and prolyl isomerase for proper folding.
Protein disulfide isomerase catalyzes the exchange between free Cysteines and disulfide bonds which facilitate the formation of correct disulfide bonds in protein.
Prolyl isomerase catalyzes the conversion between trans and cis Proline which is required for the proper folding of some proteins.

Question 6

amyloidosis

Answer 6

mis-folded proteins causing disease in other areas

Question 7

Prion disease

Answer 7

Normal prion protein is alpha-helix rich, becomes beta-sheet rich. This misfolded protein is infectious.

Question 8

How to purify proteins?

Answer 8

The three major protein purification approaches include:
1.) gel filtration chromatography (separates proteins based on size)
2.) ion-exchange chromatography (separates proteins based on charge)
3.) affinity chromatography (utilizes the ability of proteins to bind specific ligands)
Protein purities are often monitored using gel electrophoresis on a SDS polyacylamide gel.

Question 9

How determine things about protein?

Answer 9

The mass of the protein can be accurately determined by mass spectrometry.
The N-terminal sequence of the protein can be determined by Edman degradation.
Proteins can be identified on a Western blot using protein-specific antibodies.