Macmillan Learning
Sickling occurs in deoxyhemoglobin S but not in oxyhemoglobin S. Oxyhemoglobin has a small, hydrophobic pocket in a ?
chain region 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 candidates for the pocket-Val 6 interaction.
? leucine
? glutamine
? serine
? glutamate
? phenylalanine
How does HbS aggregation occur in sickle-cell anemia? Place the steps in the correct order. Note that deoxyhemoglobin is in
the T state; oxyhemoglobin is in the R state.
No aggregation