Myoglobin and hemoglobin may be the most-studied and best-understood proteins. They were the first protein for which three-dimensional structures were determined, and our current understanding of myoglobin and hemoglobin is garnered from the work of thousands of biochemists over several decades. Most important, they illustrate almost every aspect of biochemist processes: the reversible blinding of a ligand to a protein. This classic model of protein function will tell us a great deal about how proteins work.
Oxygen is poorly soluble in aqueous solutions and cannot be carried to tissues in sufficient quantities if it is simply dissolved in blood serum. Diffusion of oxygen through tissues is also ineffective over distances greater than few millimeters. The evolution of larger, multicellular animals depended on the evolution of protein that could transport and store oxygen. However, none of the amino acid side chains in protein is suitable for the reversible binding of oxygen molecule. This role is filled by certain transition metals, among them iron and copper, that have a strong tendency to bind oxygen.
[...] Some of these agents work by trying to induce the body to produce more fetal hemoglobin (therefore decreasing the amount of sickling) or by increasing the binding of oxygen to sickle cells. But as yet, there are no other widely used drugs that are available for treatment. Bone marrow transplants are currently the only potential cure for sickle cell anemia. In this treatment the patient's bone marrow (which makes the sickled red blood cells) is replaced with bone marrow from another individual without sickle cell disease. [...]
[...] This adjustment in the BPG level has only a small effect on the binding of oxygen in the lungs but a considerable effect on the release of oxygen in the tissues. As a result, the delivery of oxygen to the tissues is restored to nearly 40% of that which can be transported by the blood. The situation is reversed when the person returns to sea level. The BPG concentration in erythrocyte also increases the in people suffering from hypoxia, lowered oxygenation of peripheral tissues due to inadequate function of lungs or circulatory system. [...]
[...] There are a variety of oxygen transport and binding proteins throughout the animal (and plant) kingdom. Myoglobin: Found in the muscle tissue of many vertebrates including humans (gives muscle tissue a distinct red or dark gray color). Is very similar to hemoglobin in structure and sequence, but is not arranged in tetramers and lacks cooperative binding and is used to store oxygen rather then transport it. Hemocyanin: Second most common oxygen transporting protein found in nature. Found in the blood of many arthropods and molluscs. [...]
[...] Symptoms joint pain and other bone pain fatigue breathlessness rapid heart rate delayed growth and puberty susceptibility to infections ulcers on the lower legs (in adolescents and adults) jaundice bone pain attacks of abdominal pain fever Additional symptoms that may be associated with this disease: bloody urine (hematuria) excessive urination, excessive volume thirst, excessive unwanted painful erection (priapism; this occurs in 10-40% of men with the disease) chest pain poor eyesight/blindness Signs and tests Common signs include: paleness yellow eyes/skin growth retardation Tests commonly performed to diagnose and monitor patients with sickle cell anemia include: Complete blood count (CBC) Hemoglobin electrophoresis Sickle cell test Patients with sickle cell may have abnormal results on certain tests, as follows: peripheral smear displaying sickle cells urinary casts or blood in the urine Hemoglobin; serum decreased elevated bilirubin high white blood cell count elevated serum potassium elevated serum creatinine blood oxygen saturation may be decreased CT scan or MRI can display strokes in certain circumstances Treatment Patients with sickle cell disease need certain treatment and follow-up even when not having a painful crisis. [...]
[...] STRUCTURE OF MYOGLOBIN Hemoglobin Undergoes a Structural Change on Binding Oxygen X-rays analysis has revealed two major confirmations of hemoglobin: the R state and the T state. Although oxygen binds to hemoglobin in either state, it has a significantly higher affinity for hemoglobin in the R state. Oxygen binding stabilizes the R state. When oxygen is absent experimentally, the T state is more stable and is thus the predominant confirmation of deoxyhemoglobin. T and R originally denoted and respectively, because the T state is stabilized by a greater number of ion pairs, many of which lie at the α1β2 (and α2β1) interface. [...]
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