Biochemistry

Hemoglobin types. Heme in the formation of hemoglobin binds to globin. Globin is a protein close to albumin by its properties. The connection between heme and globin is carried out using the histidine imidazole core which is part of the globin. Hemoglobin is the main protein of red blood cells. It contains 0.338% iron. Hemoglobin is built of four subunits, each of which is a polypeptide. Every two polypeptides are identical in structure. The molecular weight of the subunit is 16,500, therefore, the molecular weight of hemoglobin is 66,000. Each subunit is associated with one heme molecule and all four hemes are on the surface of the common molecule. The binding of hemes to the globin subunits leads to the hemoglobin molecule stabilization. Hemoglobin breakdown. Red blood cells are phagocytosed by cells of the reticuloendothelial system (macrophages) 120-130 days after their appearance in the bone marrow and appearing in the blood. Macrophages are found mainly in the spleen, liver and bone marrow. Red blood cells are destroyed and their main component, hemoglobin breakdown in macrophages. Verdihemoglobin colored in green is formed when the bridges connecting the pyrrole nuclei are broken in heme. Verdihemoglobin then breaks down with the release of globin, iron and biliverdin. From biliverdin, bilirubin is formed as a result of reduction. The iron released from the heme is bound by a plasma protein (P-globulin) and transported to the liver, where it is deposited in the form of ferritin or delivered to the bone marrow, where new red blood cells are used to synthesize hemoglobin. The bilirubin formed in reticuloendothelial cells in the form of a complex with a protein is delivered by the blood to the liver. This complex disintegrates in the liver, and the released bilirubin enters into the bile ducts, and then through the ducts into the gallbladder. Bilirubin in the form of a component of bile from the gallbladder enters into the duodenum. Bilirubin is restored with the formation of a colorless mesobilirubinogen in the intestine, under the influence of the intestinal flora, from which various pigments arise. A certain amount of stercobilinogen, formed in the intestine from mesobilirubinogen, is absorbed by the intestine into the blood, which delivers it to the liver. Part of stercobilinogen from the liver, along with bile, enters the intestine, and the rest of it is delivered with blood to the kidneys and excreted in the urine. 177