Chapter 25.2, Problem 8CC

(a)

Interpretation Introduction

Interpretation:

Amino acid with the lowest pI value needs to be identified from the given set of amino acids.

Concept introduction:

Amino acids at a particular pH do not migrate in an electric field.  This pH is known as the isoelectric point.  The isoelectric point is also known as isotonic point.  At this isoelectric point the amino acid is neutral.  This means that the zwitterion form predominates more over the other forms.  pI is the isoelectric point and this can be given by average of the pK_a.

$\text{pI=}\frac{{\text{pK}}_{{\text{a}}_{\text{1}}}{\text{+pK}}_{{\text{a}}_{\text{2}}}}{\text{2}}$

The amino acid which has more acidic groups is said to have lower pI value and the compound which has more basic groups is said to have higher pI value.

To find: the amino acid possessing the lowest pI from the given set of amino acid

(b)

Interpretation Introduction

Interpretation:

Amino acid with the lowest pI value needs to be identified from the given set of amino acids.

Concept introduction:

Amino acids at a particular pH do not migrate in an electric field.  This pH is known as the isoelectric point.  The isoelectric point is also known as isotonic point.  At this isoelectric point the amino acid is neutral.  This means that the zwitterion form predominates more over the other forms.  pI is the isoelectric point and this can be given by average of the pK_a.

$\text{pI=}\frac{{\text{pK}}_{{\text{a}}_{\text{1}}}{\text{+pK}}_{{\text{a}}_{\text{2}}}}{\text{2}}$

The amino acid which has more acidic groups is said to have lower pI value and the compound which has more basic groups is said to have higher pI value.

To find: the amino acid possessing the lowest pI from the given set of amino acid