Exam 6: The Three-Dimensional Structure of Proteins

Which of the following is considered a dead-end complex (and therefore dangerous due to its resistance to proteolytic cleavage)in the protein-folding pathway?

Which of the following structural proteins is correctly paired with the modified amino acid or cross-link that is an integral part of that protein?

Which of the following is a highly compact structure that is very commonly used to transition from one region of secondary structure to another in a globular protein?

The presence of a hydrophobic amino acid at every third or fourth residue in $\alpha$ -keratin results in which of the following?

What type of interaction occurs between the $\beta$ -sheets of fibroin?

Show the reaction catalyzed by prolyl isomerase.Indicate the configuration of both substrate and product.

In a typical Ramachandran plot,_____ is plotted vs _____ to illustrate _______.

Which of the following could contribute to quaternary structure?

Show the most likely interaction that would occur between a serine residue and a glutamine residue.

Draw a section of antiparallel $\beta$ -sheet showing two sheets with three residues in each sheet.Clearly show the hydrogen bond pattern between the two sheets.

Which of the following causes denaturation of a protein when disulfide bonds are present?

Of the following proteins that aid in the folding process,which is exclusively involved in the interconversion of cis and trans bonds?

Which of the following types of secondary structure has a non-integer value of residues per turn?

A protein with five disulfide bonds was treated with $\beta$ -mercaptoethanol and urea.Once the protein was denatured,the $\beta$ -mercaptoethanol and urea were removed by dialysis.What is the likelihood that all five disulfide bonds will reform correctly?

Which of the following correctly defines the angles $\varPhi$ and $\varPsi$ ?

Which amino acid is often referred to as a "helix-breaker" due to its absence from $\alpha$ -helices but is often found in structures such as $\beta$ -turns?

Which of the following contributes to a positive $\Delta$ G for protein folding?

Which of the following is true regarding $\beta$ -sheet structures?

If a peptide was composed entirely of $\alpha$ -helical structure and found to contain an integer number of complete turns,which of the following would be a possible number of amino acid residues in the peptide?

The two amino acids most often found in a polyproline II helix are proline and _______.