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Unformatted text preview: W is ~ 40000. The main stimulus for erythropoietin secretion is Hypoxia. Androgens (male sex hormones) also stimulate secretion erythropoietin. Erythropoietin acts on red bone marrow increasing the production of RBC’s. It increases the production of proerythroblasts from the committed stem cells of bone marrow and it also speeds up the division of the erythroblasts and therefore the end result will be more RBC’s formation. Hemoglobin Hemoglobin It is a protein with MW of ~ 64000. It consists of 4 subunits, each one contains a heme moiety conjugated to a polypeptide. Heme is a porphyrin with iron atom in a ferrous state (Fe2+). There are two pairs of polypeptides in each Hb molecule. Hemoglobin Hemoglobin ­ HbA (adult Hb) 2 alpha + 2 β 141 a.a 146 a.a ­ HbA2 (about 2.5% of Hb in adults is HbA2) 2 alpha + 2 δ Delta ­ HbF (Hb during fetal life) 2 alpha + 2 Gamma Hemoglobin Hemoglobin Substitution of one or more of amino acids in the polypeptide changes the characteristic features of the Hb molecule, for Ex. HbS (Sickle Hb) contains...
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This document was uploaded on 02/05/2014.

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