Lecture 7 Protein Folding II

Question 1

be familiar with the topics for PROTEINs

3 STABILITY MECHS
DENATURATION 6 WAYS
ANALYSIS 5 WAYS
3 ACCESSORY

Answer 1

Protein

Question 2

Protein turnover is important b/c?

Answer 2

This is how Biological function of the cell is regulated through the synth and degradation of proteins

Question 3

what does it mean for a protein to be stable

Answer 3

It is active and in its intact/folded and native state.

Question 4

Name and define the 3 properties of a protein itself that contributes to protein stability? and what level of structure is this important at?

Answer 4

ITS IMPORTANT FOR TERTIARY STRUCTURE
1 Disulfide bonds - Extracellularly ONLY, these bonds between 2 cysteine residues provide stability
2. Hydrophobic effect - attraction of non polar residues
3. Oligameric Structures - the formation of monomers binding to form dimers, trimeric, tetrameric proteins etc.

Question 5

Protein instability is referred to as? And basically helps promote protein _______?

Answer 5

UPS and UPR, Unfolded Protein Stress or Response to proteins that are incorrectly folded in any way.
Promotes protein turnover.

Question 6

UPR begins in the ____?

Answer 6

ER

Question 7

Protein denaturation is when?

Answer 7

The hydrophobic (internal) parts, get turned inside out and then attract other hydrophobic parts and this results in that color change or from clear to white.

Question 8

6 Major ways to Denature a Protein? (2 categories of 3 ways each )

Answer 8

3 conditions and 3 Chemicals

conditions: Heat, pH, agitation/pressure
chemicals: Detergents, organic solvents, chaotropic agents

Question 9

Have memorized these 3 chaotropic agents that denature proteins?

Answer 9

urea, beta mercaptoethanol, Guanidinium chloride.

Question 10

Which 2 chaotropic agents reduce ribonucleases?

Answer 10

urea and beta Mercaptoethanol

Question 11

Name the 3 accessory proteins and what they do ?

Answer 11

PDI, PPI, Molec Chaperones help control Protein Unfolding or misfolding

Question 12

PDI stands for and does what?

Answer 12

Protein Disulfide Isomerase is an accessory protein that sees mistakes in Disulfide bonding/folding and corrects it.

Question 13

PPI stands for and does what?

Answer 13

Protein Prolyl Isomerases,. recognizes if prolines orientated substituents are incorrectly Cis/trans and corrects them.

Question 14

Molecular chaperones, aka? and do what

Answer 14

HSP = heat shock proteins, help with correcting of Misfolded and unfolded proteins

Question 15

Whats HSP 90 do?

Answer 15

for signal transduction prots, b/c it allows proteins to be unfolded so that it can have multiple binding sites.

Question 16

Whats HSP 27 do?

Answer 16

Prevents aggregation and helps with folding.

Question 17

HSP 70 and 40

Answer 17

are ATP driven to reverse misfolds, and unfold and refold trafficked proteins, and push them back through the ER.

Question 18

What are the 2 mech. for chaperonins?

Answer 18

both do into basket refold and out of basket.

1 is passive = Anfensen Cage 2. is active Itterative Annealing, pulls apart so it can correctly refold.

Question 19

Protein analysis, 5 ways are?

Answer 19

1. turbidity (agitation) 2. Circular dichroism (looking @ secondary struct.)
2. UV absorption (connected to Aromatic A.A.)
3. fluorescence
4. biological Activity ( Folded=active, unfolded = inactive)