PROTEIN STABILITY Questions and Answers pdf :-

1. Unpaired H-bond donors and acceptors are found in the hydrophobic core of a protein

A. only at the ends of a-helices
B. only at the turns connecting p-strands
C. only on Pro residues
D. rarely

Answer: D

2. For the unfolding reaction of Protein G, ?H° =210.6 kJ/mol, this means that

A. unfolding is favored enthalpically
B. folding is favored enthalpically
C. the entropy is positive at all temperatures
D. the entropy is negative at all temperatures

Answer: B

3. Attractive Vander Waals forces occur between

A. apolar molecules in the liquid state
B. any pair of nearby atoms
C. polar molecules in the solid state
D. only if other forces are less favorable

Answer: B

4. Which of the following forces is the most favorable for protein folding?

A. Conformational entropy
B. Hydrophobic Interactions
C. Vander Waals interactions
D. Hydrogen bonds

Answer: B

5. At the midpoint of a temperature transition curve,

A. half of the protein is denatured
B. Keq = 1.0 and ?G = 0
C. [Native] = [Unfolded]
D. All of these

Answer: D

6. Which of the following is the most correct?

A. Charged amino acids are never buried in the interior of a protein
B. Charged amino acids are seldom buried in the interior of a protein
C. All hydrophobic amino acids are buried when a protein folds
D. Tyrosine is only found in the interior of proteins

Answer: B

7. Which of the following forces is the most unfavorable for protein folding?

A. Conformational entropy
B. Hydrophobic interactions
C. Vander Waals interactions
D. Electrostatic interactions

Answer: A

PROTEIN STABILITY Questions and Answers ::

8. Since ?G° = -RTlnK

A. a 10-fold increase in K decreases ?G° by about 10-fold
B. a 10-fold decrease in K decreases ?G° by about 2.3*RT
C. a 10-fold increase in K decreases ?G° by about 2.3*RT
D. a 10-fold decrease in K increases ?G° by about 10-fold

Answer: C

9. The correlation between free energy ?G transfer between the aqueous/organic phases and the surface area of amino acid residues

A. reflects the reduction in solvent-accessible area during protein folding
B. is only meaningful for the polar amino acids
C. ignores the important contribution of the peptide bond
D. is similar to effects seen with SDS denaturation

Answer: A

10. If the egg white protein, ovalbumin, is denatured in a hard-boiled egg, then which of the following is least affected?

A. The primary structure of ovalbumin
B. The secondary structure of ovalbumin
C. The tertiary structure of ovalbumin
D. The quaternary structure of ovalbumin

Answer: A

11. Buried hydrophobic side chains in a globular protein fit into a hole formed by the side chains of

A. 1-3 other amino acids
B. 5-7 other amino acids
C. 9-12 other amino acids
D. 13-15 other amino acids

Answer: B

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