1. The level of protein structure that is stabilized primarilyby non-covalent interactions between the side chains within asingle polypeptide chain is refered to as its:
A) primary structure
B) secondary structure
C) tertiary structure
D) quaternary structure
E) none of the above
2. Collagen, a strong fibrous protein found in connectivetissue, bone, and the extracellular matrix, has a structure inwhich three left-handed helices wind around each other to form aright-handed triple helix. The primary structure of collagen has arepeat unit of -(Gly-X-Pro)- Which of the following bonds stabilizethe collagen triple helix? (mark all that apply)
A) Hydrogen bonds between hydroxyproline residues
B) Hydrogen bonds between N-H and C=O
C) Ionic bonds between amino acid side chains
D) Hydrogen bonds between charged amino acids
3. The non-covalent forces that stabilize the Beta-strandconformation of peptides include:
A) H-bonds between amide C=O and amide NH
B) Van der Waals packing between the peptide backbone atoms
C) Van der Waals packing due to side chain interdigitation
D) Only A and B above
E) None of the above
4. What is the approximate length difference of a 22-kDasingle-stranded ?-helical protein segment vs. a 22-kDasingle-stranded ?-strand protein segment? Assume a mean residuemass of 110 Da. Show work.
5. Circular dichroism measurements have shown that the peptidebackbone of poly-l-lysine (KKKKKKK) adopts a random coilconformation at pH 7.0, but becomes ?-helical as the pH is raisedabove 10. This observation is known as the
