Protein Stability problems
- 1. For the unfolding reaction of Protein G, ∆H° =210.6 kJ/mol, this means that
Options- 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 Discuss
Correct Answer: folding is favored enthalpically
- 2. The correlation between free energy ?G transfer between the aqueous/organic phases and the surface area of amino acid residues
Options- 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 Discuss
Correct Answer: reflects the reduction in solvent-accessible area during protein folding
- 3. Buried hydrophobic side chains in a globular protein fit into a hole formed by the side chains of
Options- A. 1-3 other amino acids
- B. 5-7 other amino acids
- C. 9-12 other amino acids
- D. 13-15 other amino acids Discuss
Correct Answer: 5-7 other amino acids
- 4. Unpaired H-bond donors and acceptors are found in the hydrophobic core of a protein
Options- A. only at the ends of a-helices
- B. only at the turns connecting p-strands
- C. only on Pro residues
- D. rarely Discuss
Correct Answer: rarely
- 5. Since ?G° = -RTlnK
Options- 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 Discuss
Correct Answer: a 10-fold increase in K decreases ?G° by about 2.3*RT
- 6. At the midpoint of a temperature transition curve,
Options- A. half of the protein is denatured
- B. Keq = 1.0 and ?G = 0
- C. [Native] = [Unfolded]
- D. All of these Discuss
Correct Answer: All of these
- 7. Which of the following is the most correct?
Options- 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 Discuss
Correct Answer: Charged amino acids are seldom buried in the interior of a protein
- 8. Which of the following forces is the most unfavorable for protein folding?
Options- A. Conformational entropy
- B. Hydrophobic interactions
- C. Vander Waals interactions
- D. Electrostatic interactions Discuss
Correct Answer: Conformational entropy
- 9. Attractive Vander Waals forces occur between
Options- 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 Discuss
Correct Answer: any pair of nearby atoms
- 10. Which of the following forces is the most favorable for protein folding?
Options- A. Conformational entropy
- B. Hydrophobic Interactions
- C. Vander Waals interactions
- D. Hydrogen bonds Discuss
Correct Answer: Hydrophobic Interactions
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