Answer: Valine
Explanation:
hemoglobin A (normal) is HbA, while hemoglobin S (present in people with sickle cell anemia) is HbS
A sequence of 146 amino acids is present in the Hemoglobin.
The first 6 amino acids in HbA are: valine, histidine, leucine, threonine, proline, and glutamic acid.
The first six amino acids in HbS is:
valine, histidine, leucine, threonine, proline, and VALINE
In Hbs, the 6th amino acid (Glutamic acid) has already been mutated to Valine, a nonpolar, branched amino acid.
