Download Ch 4 Reading Guide

Reading Guide, Stryer Short Course, Chapter 4
1. Draw the tripeptide Gly-Phe-Leu at pH 7.4. Indicate the backbone, one peptide bond, and one
sidechain.
2. Give three reasons it is important to know the primary sequence of a protein.
3. Give a chemical explanation of why a peptide bond is planar.
4. Why are almost all peptide bonds in proteins trans rather than cis.
5. Regular, folded segments of amino acids near one another in linear sequence is called
____________________ structure.
6. In the -helix, a _____________________ bond is formed between the CO group of residue i
and the NH group of residue i + ____.
7. The amino acid ___________________ is a helix breaker because it has no NH bond to serve
as a hydrogen bond donor.
8. How are parallel and antiparallel sheets similar? How are they different?
9. Reverse turns and loops invariably lie on the ___________________ of proteins, and thus
often participate in interactions between _____________________.
10. Compare and contrast the structures of the proteins collagen and keratin.
11. The tertiary fold of a protein results in the interior consisting of almost entirely
______________________ residues.
12. How are hydrogen bonds maintained in the interior of a globular protein?
13. Define motif (super-secondary structure.)
14. Define domain.
15. Quaternary structure refers to the arrangement of _______________ and the nature of their
interactions.
16. Explain the experiment that Anfinsen used to show that the information needed to specify the
catalytic activity of ribonuclease was contained in its primary structure.
17. What is the average difference in energy between a folded and unfolded protein? Is this
amount of energy relatively large or small?
18. Do all proteins follow the paradigm of one sequence = one structure?
19. List a few diseases that arise from protein misfolding and aggregation.