Basic defect in HbS is?
Basic defect in HbS is altered solubility. A molecule of hemoglobin S (HbS) contains two normal a globin chains and two mutant b globin chains- glutamate at position 6 is substituted with valine. This replaces the polar glutamine residue with a nonpolar valine. The replacement of glutamate by valine generates a sticky patch on the surface of HbS. The sticky patch is present on both oxygenated and deoxygenated HbS but deoxygenated HbS also contains a complementary site for the sticky patch. When HbS is deoxygenated the sticky patch present on its surface binds to the complementary patch on another deoxygenated HbS molecule. Binding of a number of deoxygenated HbS leads to formation of long fibrous polymers of HbS. This stiffens and disto the red cells producing rigid misshaped erythrocytes.
Altered function
Altered solubility
Altered stability
Altered O2 binding capacity
Sickle Cell Disease, G6PD deficiency and other Hemolytic Anemia