Question

Where are valine and glutamic acid normally found?

Answer 1

Valine and Glutamic acid are found in proteins.

Glutamic acid has a negative charge and is therefore hydrophilic. Since hydrophilic, they are usually found at the surface of a water-soluble proteins.

Valine has a neutral charge, is hydrophobic, and is thus present in the interior of a globular protein.

A classical example where the effect of amino acid substitution from hydrophilic to hydrophobic can be studied is in case of sickle cell anemia. A glutamic acid residue in normal hemoglobin is replaced by a valine residue.

When the molecule is hydrophilic, erythrocytes have a normal shape and flow as they should. When the molecule is hydrophobic, the shape is distorted and the erythrocytes can more easily stick together to form blockages.