Question

Draw zwitterion forms of these amino acids. (a) Valine (b) Phenylalanine (c) Glutamine

Short answer

Answer: The zwitterion forms of Valine, Phenylalanine, and Glutamine are as follows: (a) Valine: H | -N-CH-COO(-) | |-CH(CH3)2 (b) Phenylalanine: H | -N-CH-COO(-) | -CH2-C6H5 (c) Glutamine: H | -N-CH-COO(-) | -CH2-CH2-CONH2

Step-by-step solution

Understand the structure of an amino acid

An amino acid has a central carbon atom known as the alpha carbon, bonded to four different groups: an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (-H), and a side chain (-R group) that differs between various amino acids.

Determine the functional groups of each amino acid

Identify the functional groups present in Valine, Phenylalanine, and Glutamine: (a) Valine - It has an amino group (-NH2), a carboxyl group (-COOH), and a side chain (-CH(CH3)2). (b) Phenylalanine - It has an amino group (-NH2), a carboxyl group (-COOH), and a side chain (-CH2-C6H5). (c) Glutamine - It has an amino group (-NH2), a carboxyl group (-COOH), and a side chain (-CH2-CH2-CONH2).

Draw the zwitterion forms of each amino acid

The zwitterion forms of Valine, Phenylalanine, and Glutamine result from deprotonation of the -COOH group and protonation of the -NH2 group. This creates a negative charge on the oxygen atom in the carboxyl group and a positive charge on the nitrogen atom in the amino group. The side chains remain unchanged. (a) Valine: H | -N-CH-COO(-) | |-CH(CH3)2 (b) Phenylalanine: H | -N-CH-COO(-) | -CH2-C6H5 (c) Glutamine: H | -N-CH-COO(-) | -CH2-CH2-CONH2