What is the major consequence of the amino acid change associated with Hgb S?

The major consequence of the amino acid change associated with Hgb S (hemoglobin S), which is the abnormal hemoglobin found in sickle cell disease, is a decreased rate of migration toward the anode during electrophoresis. This occurs because Hgb S has a different charge compared to normal hemoglobin (Hgb A) due to a substitution of valine for glutamic acid at the sixth position of the beta-globin chain. This change reduces the negative charge of hemoglobin, resulting in slower movement toward the anode when an electric current is applied, as proteins with a more negative charge migrate faster in an electric field.

In contrast, options regarding increased migration or enhanced properties such as hemoglobin solubility or oxygen binding capacity do not apply to Hgb S. The substitution of amino acids leads to the formation of sickle-shaped red blood cells that have altered properties compared to normal red blood cells, impacting their behavior in various physiological contexts, including the ability to carry oxygen efficiently.