3. Amino Acids

Which shows the proper structure of Leu at physiological pH?

Fill in the groups for the predominant structure of Ala at pH 13?

Fill in the appropriate groups for Asp at pH 4.3.

Draw the predominant structure of Arg at pH 6.5? (pK _a1 = 9.04, pK_a2 = 2.17, pK_a3 = 12.48).

At what pH would an amino acid bear both a neutral -COOH and a -NH ₂ group?