Question

Question 11. Certain amino acids destabilize or prevent formation of alpha-helices. Which amino acid is more likely to be found in these structures based on its charge and R-group size? A. Glycine B. Proline C. A sequence of several Glutamate D. A sequence of several Lysine E. Alanine Question 12. Which of the following is least likely to result in protein denaturation? A) Altering net charge by changing pH B) Changing the salt concentration C) Disruption of weak interactions by boiling D) Exposure to detergents E) Mixing with organic solvents such as acetone Question 13. Roughly how many amino acids are there in one turn of an alpha helix? A) 1 20: All of B) 3.6 C) 4.2 D) 10 Ruestion 14. Amino acid residues commonly found in the middle of B turn are- A. Ala and Gly B. hydrophobic. C. Pro and Gly D. those with ionized R-groups. E two Cys.. Ruestion 15. Which of the following best represents the backbone arrangement of two peptide onds? A) Ca-N-C.-C-C.-N-C.-C B) Cu-N-C-C-N-C C) Ca-C-N-C.-C-N D) C.-C.-C-N-C.-C.-C Question 16. In an aqueous solution, protein conformation is determined by two major factors. ne is the formation of the maximum number of hydrogen bonds. The other is the: A) formation of the maximum number of hydrophilic interactions. B) maximization of ionic interactions. C) minimization of entropy by the formation of a water solvent shell around the protein. D) placement of hydrophobic amino acid residues within the interior of the protein. E) placement of polar amino acid residues around the exterior of the protein.

Answer 1

11) Proline and glycine are sometimes known as helix breakers because they disrupt the alpha helical back bone conformation; however both have unusual conformational abilities and are commonly found in turns. Amino acid that prefer to adopt helical conformations in proteins include lysin,glutamate ,alanine etc.

12) Detergents can be denaturing or non denaturing depending upon the protein structure. So it is least likely to cause protein denaturation.

13) Alpha helices have 3.6 anino acid residues per turn.

14) Proline and glycine are found in beta turns.

15) C-C-N-C-C-N

16) Placement of hydrophobic amino acid residues with in the interior of the protein.