Chapter 27, Problem 27.33P

Interpretation Introduction

Interpretation:

Enzyme catalysed decarboxylation of Glutamic acid gives 4-aminobutanoic acid. The $\text{pI}$ value of the 4-aminobutanoic acid has to be estimated.

Concept Introduction:

The isoelectric point of an amino acid is $\text{pH}$ at which the molecules in solution have net charge of zero.  The isoelectric point is calculated by using the formula

  $pI=\frac{1}{2}\left(p{K}_a\alpha -COOH+p{K}_a\alpha -N{H}_3{}^{+}\right)$

If the amino acids contains side chains, then for acidic side chain amino acids ${\text{pK}}_{\text{a}}$ of ${\text{α-COO}}^{\text{-}}$ and ${\text{pK}}_{\text{a}}$ of side chain ${\text{–COO}}^{\text{-}}$ can be calculated and for basic side chain amino acids, ${\text{pK}}_{\text{a}}$$\text{pKa}$ of ${\text{α-NH}}_{\text{3}}$ and ${\text{pK}}_{\text{a}}$$\text{pKa}$ of side chain ${\text{–NH}}_{\text{3}}$ can be calculated.