Protein folding and Thermodynamics

Question 1

Anfinsen’s experiment

Answer 1

1. Unfolded proteins are inactive ∴ Structure ➝ Activity. 2. Correct disulphide bond formation occurs after folding. 3. All the information for a protein to fold correctly is
   contained in the amino acid sequence.
2. Disulphide bonds stabilise folded proteins.

Question 2

What directs protein folding

Answer 2

The different types of bonds or interactions make different contributions to protein folding, they have different strengths, directional properties and roles in folding

Question 3

Thermodynamics

Answer 3

The alteration of the content of energy and its distribution that take place when a system passes from an initial, defined state into a terminal state @equilibrium

Question 4

∆X - the change in X

Answer 4

changed in temp ∆X is defined as ∆T= Tfinal - Tinitial

Can be applied to chemical or physical changes

Question 5

Laws of themodynamics

Answer 5

1.Energy can never be created or destroyed

Question 6

If the energy of a system changes the energy must be transferred to another system

Answer 6

∆U= q+w q=heat w=work

Question 7

Enthalpy

Answer 7

∆U=q+w
at constant pressure q=∆U (change in enthalpy)
If heat is released the system has a decrease in enthalpy (∆H<0) and is exothermic
If heat is absorbed the system has an increase in enthalpy (∆H>0) and is endothermic

STANDARD
Pressure 10^5 Pa
Concentration of 1M

Question 8

Hess’s law

Answer 8

The overall enthalpy change for any process is constant, regardless of how the reaction is carried out

Question 9

Entropy

Answer 9

Amount of disorder
∆rS= Sproducts - Sreactants
J mol-1 K-1
ANY EVENT THAT IS ACCOMPANIED BY AN INCREASE IN THE ENTROPY OF THE SYSTEM HAS A TENDENCY TO OCCUR SPONTANEOUSLY

Question 10

Gibbs energy (G)

Answer 10

Entropy change of the universe: ∆Stotal= ∆Ssystem +∆Ssurroundings

∆Stotal= ∆Ssystem - ∆Hsystem
T
G=H-TS
A process is spontaneous when ∆G<0 at constant p and T

Question 11

protein folding the free energy change associated

Answer 11

DGtotal = DHchain+ DHsolvent - T DSchain -T DSsolvent