Lecture 7 Protein Folding II

Question 1

4 Conditions that cause protein denaturation

Answer 1

1. Heat
2. pH (extremes)
3. Agitation
4. Chemicals
   - Detergents
   - Chaotropic agents
   - Organic solvents

Question 2

Heat Denaturation

Answer 2

Ex. Frying an egg.. White part is clear protein, albumin

When white is denatured

Question 3

pH Denaturation

Answer 3

Extreme pH

Ex. Seviche - lemon juice on shrimp

Question 4

Agitation Denaturation

Answer 4

Ex. Meringue and concussion in humans

Question 5

3 Types of Chemical Denaturation

Answer 5

1. Detergents
2. Chaotropic agents
3. Organic solvents

Question 6

Detergent Denaturation

Answer 6

Ex. Clothes, detergents - has charged components

Most harsh has ionic with head and tail - micelles

Question 7

Chaotropic agents Denaturation

Answer 7

Urea

Guanifium chloride

Question 8

Orgainic solvents Denaturation

Answer 8

Ex. Cooking brats in beer

Question 9

5 Methods of Protein Denaturation Analysis

Answer 9

1. Turbidity
2. Circular dichroism
3. UV Absorption
4. Fluorescence
5. Biological Activity

Question 10

Turbidity

Answer 10

Method of analysis for protein denaturation

Uses UV spec to see when gets milky

Question 11

Circular Dichroism

Answer 11

Method of analysis for protein denaturation

Looks at circular structure, Beta and alpha content

Question 12

UV Absorption

Answer 12

Method of analysis for protein denaturation

Look at 280nm, based on aromatics, tyrosine, tryptophan

Question 13

Fluoresence

Answer 13

Method of analysis for protein denaturation

Need less to look at this, bigger change

Question 14

Urea

Answer 14

Protein denaturation
Reducing agent
Urea breaks weak bonds

Question 15

B-mercaptoethanol

Answer 15

Protein denaturation
Reducing agent
Reduces disulfide bridges

Question 16

3 Types of Accessory Proteins

Answer 16

1. PDI
2. PPI
3. Molecular chaperones

Question 17

PDI

Answer 17

Accessory proteins
Protein disulfide isomerases
Covalent disulfide bridges that are built wrong

Question 18

PPI

Answer 18

Accessory proteins
Protein cis-trans prolyl isomerases
2 states - cis and trans
Occurs when it turns, one L conformation the other is strongly wrong

Question 19

5 Types of Molecular Chaperones

Answer 19

1. HSP 70 (HSP 40)
2. Chaperonins
3. HSP 90
4. Nucleoplasmins
5. small HSP

Question 20

HSP 70

Answer 20

(HSP 40) *these work together
ATP driven
Functions - reverses misfolds, newly synthesized proteins, unfold/refold of trafficked proteins

Question 21

HSP 70 Function

Answer 21

(ATP driven)

Reverses misfolds, newly synthesized proteins, unfold/refold of trafficked ptoteins

Question 22

HSP 90

Answer 22

Signal transduction proteins

Highly abundant in cell

Question 23

Protein Turnover

Answer 23

No matter how long around, even connective tissues still get turned over because structure gets compromised

Question 24

Protein stability

Answer 24

Why structure is important

Question 25

3 Levels of Symmetry

Answer 25

1. Cyclical
2. Dihedral
3. Screw symmetry

Question 26

Cyclical symmetry

Answer 26

2 fold or 3 fold rotation

Ex. 1/2 pepperoni 1/2 cheese

Question 27

Dihedral symmetry

Answer 27

Can rotate circularly and can flip around

Question 28

Screw symmetry

Answer 28

Aka helical actin filament, looking down acis and rotate = screw/helix

Question 29

Dogma

Answer 29

1 AA = 1 protein = 1 function
NOT true
1 protein = many structures = many functions

Question 30

Metamorphic proteins

Answer 30

Have multiple conformations that are stable and bind different things

Question 31

UPR

Answer 31

Unfolded Protein Response
Leads to a lot of pathologies
Ex oxidative stress, free radicals

Question 32

Chaperonis mechanism

Answer 32

Can occur 10-13x until folding is fixed