Question

Aspartame (its structure is on page 1007) has a pI of 5.9. Draw its prevailing form at physiological pH (7.4).

Short answer

Structure of aspartame at =7.4 is shown below:

Structure of aspartame at =7.4

Step-by-step solution

Relation between pH and pI value 

Isoelectric point of an amino acid can be seen in structures that contain both positive and negative charges.AMolecule having both positive and a negative charge in its structure is characterized as a zwitterion. Amino acid exists in deprotonated form athigher than pI value.On the other hand, amino acid exists as a protonated form while ph less than pI.

Possible structure of aspartame at pH =7.4

Structure of aspartame at =7.4

Thus, the prevailing structure of aspartame at =4 is drawn.