Question

The isoelectric point of the given amino acid is

• A. 6.62
• B. 5.24
• C. 1.1
• D. 2.76

Answer 1

The correct option is D 2.76

A certain pH at which the concentration of the dipolar ion is at its maximum and the concentrations of the anions and cations are equal is called isolelctric point.
The given amino acid is a acidic amino acid.
Given:
$p{K}_1=1.88$
$p{K}_3=3.65$
For basic amino acid,
$pI=\frac{p{K}_1+p{K}_3}{2}$

$pI=\frac{1.88+3.65}{2}$
$pI=\frac{5.53}{2}$
$pI=2.76$