Sickling occurs in deoxyhemoglobin S but not in oxyhemoglobin S. Oxyhemoglobin has a small, hydrophobic pocket in a β chain regi
on located in the interior of the protein. In deoxyhemoglobin, however, this pocket is located on the surface of the protein. In deoxyhemoglobin S, Val 6 interacts with this surface pocket, leading to aggregation of HbS. Choose two amino acids that would be reasonable canidates for the pocket-Val 6 interaction. (A) phenylalanine
(B) leucine
(C) serine
(D) arginine
(E) glutamate
Leucine and phenylalanine have hydrophobic side chains, which means that they can interact with valine in the pocket. All other aminoacids on the list have polar (two electrically charged) side chains and cannot form hydrophobic pockets.
