Question

22. Consider an alpha helix with sequence VLADWMAVELA, and consider the hydrogen bonds that are required in order to form the alpha helix. A. Fill in all of the hydrogen bonds that must form between a given residue's backbone N-H backbone C-O, or R group, indicating what the hydrogen bonding partner for each will be. For example, the C-O of V1 is a hydrogen bond acceptor of the W5 N-H hydrogen bond donor, reflected in the appropriate squares under V1 and W5. Note: some squares may be left blank: record only those interactions that are required to satisty the definition of an alpha helix. 10 11 V1 Backbone N-H R group B. Are there any backbone C-Ogroups or N-H groups whose hydrogen bonding capacity remains unsatisfied? What is the significance of this fact? C. Proline residues are often found at the termini of helices. Why? D. The figure at right contrasts an alpha helix with another type of peptide helix, the 310 helix. Note the differences in hydrogen bonding patterns between backbone atoms. As you did in part A above, record the hydrogen bonds between backbone N-H and C-O groups that are necessary to form a 3- helix. Canonical 3(10) helix Canonical a-helx V1 Backbone N-H Buckbone C o D4 R group E. The frequency of 310-helices is much lower than that of alpha helices. Can you make an argument for this observation based on the orientation of sidechains? Would a 310-helix configuration be favorable for the peptide sequence VLADWMAVELA? Canonical a-helix Canonical 3(10) helix

Answer 1

Answer 22.A)

Basically, the intramolecular hydrogen bonds are formed. They are formed between amino acids placed 4 amino acids apart which is seen in alpha helical structures. On that basis, above data has been stated.

DATE Backhane CN-H) BackkmeW N-H N-H N-HNH N-H N-H N-H