Achiral contains two chiral carbons. The side chain restricts the rotation of the main chain. It contains hydroxyl groups in its side chain, aromatic side chains, and carboxamide side chains. It also has positively charged side chains at pH 1, positively charged side chains at pH 7, negatively charged side chains at pH 14, and negatively charged side chains at pH 7. It is least soluble in water. It is most soluble in water. The N-terminal amino acid residue of proteins is often found in -turns and rarely found in -helices. Attachment sites of sugars in glycoproteins.
A. What is the identity of the amino acid? [Write its full name.]
B. Match the following points in the titration curve. [In the space beside each description, write a number 1-6 corresponding to a specific pH right.]
1. The amino acid is fully protonated. pH = 0.0
2. The amino acid is fully deprotonated. pH = 3.1
3. Half of the carboxyl groups are ionized. pH = 5.5
4. The average charge on the amino group is +0.5. pH = 12.5
5. The side chain has its maximum buffering capacity, functioning as an acid catalyst or base catalyst. pH = 14.0
The predominant species contains a protonated amino group, a deprotonated carboxyl group, and a protonated side chain as shown below:
HN-CH-COO
R+
