Question

Proline is an unusual amino acid because its N atom on the α carbon is part of a five-membered ring

a. Draw both enantiomers of proline.

b. Draw proline in its zwitterionic form.

Short answer

a.

Enantiomers of proline

b. Zwitterionic form of proline

Step-by-step solution

Enantiomers of a molecule

Stereoisomersthat are mirror images of each other are called enantiomers.

Enantiomers rotate plane-polarized light to the same extent but in the opposite direction.

The physical properties of enantiomers are identical except for thedirection of rotation of plane-polarized light.

Enantiomers are obtained by reversing the configuration of all the chiral carbons in the compound.

Zwitterionic form of an amino acid

Zwitterions are molecules with atleast one positive ion and a negative ion. The net charge of the molecule is zero.

Amino acids are compounds with one amino functional group and one carboxylic acid group.

In an amino acid molecule, the acid group can protonate the nitrogen in the amino group to produce ions with opposite charges. This is called a zwitterion.

Enantiomers and zwitterions of proline

a. Proline contains only one chiral carbon, and therefore the number of enantiomers of the compound will be two.

Enantiomers of proline

b. A zwitterion is formed when the nitrogen in the alpha position abstracts the hydrogen from the acid.

Zwitterionic form of proline