What is the chemical structure of hemoglobin in sickle cell anemia disease?

Answer 1

http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/blood/narrative/page17.html

Answer 2

Sickle cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S. Hemoglobin is a protein inside red blood cells that carries oxygen. Hemoglobin S, however, reduces the amount of oxygen inside the cells, distoring their shape. The fragile, sickle-shaped cells deliver less oxygen to the body's tissues, and can break into pieces that disrupt blood flow.
Clinically Significant Variant Hemoglobins
Hemoglobin S. This the predominant hemoglobin in people with sickle cell disease. The alpha chain is normal. The disease-producing mutation exists in the beta chain, giving the molecule the structure, a2bS2. People who have one sickle mutant gene and one normal beta gene have sickle cell trait which is benign.