Shown below are free energy diagrams representing the unfolding of 3 proteins (N = native; U = unfolded).

The following graph shows three protein unfolding curves.

Which of the following options is most likely to indicate the correct relationship between the three free energy diagrams and the three unfolding curves?

Shown below is a curve representing the unfolding of a protein with increasing temperature.

At what temperature are 70% of protein molecules folded?

Enter the temperature in degrees Celsius (deg C) but do NOT type the units. To be marked correct you must type only numbers.

Consider the following two ionisable groups positioned close to each other within a protein structure:

• An arginine side chain (pKa = 12.5)
• A glutamic acid side chain (pKa = 4.3)

Based on the pKa values of these functional groups and their charge states when they are ionised, select the correct statement below.

Shown below is a curve representing the unfolding of a protein with increasing temperature.

At what temperature are 70% of protein molecules folded?

Enter the temperature in degrees Celsius (deg C) but do NOT type the units. To be marked correct you must type only numbers.

Shown below are free energy diagrams representing the unfolding of 3 proteins (N = native; U = unfolded).

The following graph shows three protein unfolding curves.

Which of the following options is most likely to indicate the correct relationship between the three free energy diagrams and the three unfolding curves?

An enzyme is known to contain four Cys residues that form two disulfide bonds (and no other Cys residues).

[Note that four Cys residues could randomly form three possible disulfide bond arrangements]

A researcher performs the following sequence of treatments on a sample of this enzyme:

1. Treatment with high concentrations of mercaptoethanol and urea.
2. Simultaneous removal of the mercaptoethanol and the urea (while avoiding formation of any intermolecular disulfide bonds).

They find that the sample obtained from the final treatment has 100% of the activity of the original sample of the enzyme.

Which of the following is the best conclusion from this experiment?

Shown below is an unfolding curve for a protein that contains two domains of approximately equal size.

Which point on the curve represents the form of this protein in which one domain is fully unfolded and the other is 50% unfolded?

To test the importance of certain amino acid residues in stabilising a protein structure, a research student performs equilibrium unfolding experiments with three forms of the protein:

(A) the wild type protein;

(B) a mutant in which a slightly destabilising interaction is introduced; and

(C) a mutant in which a strongly destabilising interaction is introduced.

They obtain the three unfolding curves shown below.

Which curves correspond to which forms of the protein?

Shown below is an unfolding curve for a protein that contains two domains of approximately equal size.

Which point on the curve represents the form of this protein in which one domain is fully unfolded and the other is 50% unfolded?

Shown below is a curve representing the unfolding of a protein with increasing concentrations of guanidine hydrochloride.

At what concentration of guanidine hydrochloride are 80% of protein molecules folded?

Enter the concentration in molar but do NOT type the units. To be marked correct you must type only numbers.