Question

4) In a polypeptide, which bond cannot rotate because of its partial double bond character?

1. The C_α-R group bond
2. The N_amide-C_α bond
3. The C_carbonyl-C_α bond
4. The C_carbonyl-N_amide bond
5. All bonds are able to rotate freely

5) Which of the following best represents the backbone arrangement of two peptide bonds?

A) C—N—Cα—Cα—C—N

B) Cα—N—C—C—N—Cα

C) Cα—N—Cα—C—Cα—N—Cα—C

D) Cα—Cα—C—N—Cα—Cα—C

E) Cα—C—N—Cα—C—N

6. Describe the predominant character of the following polypeptides using the following

options

1. Nonpolar
2. Polar Uncharged
3. Polar Positively charged
4. Polar Negatively Charged

6) DETDDESD

7) RKLGRHKK

8) GVALPIVAL

Answer 1

1. In a polypeptide, the N_amide-C_α bond cannot rotate because of its partial double bond character.
2. Cα—C—N—Cα—C—N best represents the backbone arrangement of two peptide bonds.
3. The charges on the given polypeptide are as follows:

• DETDDESD: Negatively charged
• RKLGRHKK: Positively charged
• GVALPIVAL: Neutral