Question

Please please help!!

Consider three dipeptides:

    i)    S-G-K    ii) I-K-Y    iii) V-P-T

1. Draw peptide (i) illustrating the resonance structures that limit free rotation around the peptide bonds on each side of the center amino acid

2. Show which bonds have the angles we call phi () and psi (). This peptide represents a normal peptide on the Ramachandran diagram.

3. Draw peptides (ii) and (iii) and label them with phi () and psi () (don’t do the resonance structures again).

4. Which of the three peptides has the MOST movement available to it around the () and () angles of central amino acid? Why?

5. Which of the three peptides has the LEAST movement available to it around the () and () angles of central amino acid? Why?

Answer 1