You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Basic defect in HbS is? and explain in detail?
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.