About O2 dissociation curve, true is
Correct Answer: O2 affinity will be equal in both HbF and HbA in the absence of 2, 3DPG
Description: The affinity of Hb F for oxygen and carbon dioxide:The affinity of Hb F for oxygenThe affinity of Hb F for carbon dioxide1. Affinity for oxygen in case of HbF is more than that of HbA, i.e., it can take more oxygen than HbA at low oxygen pressure due to poor binding of 2,3 DPG by the gamma polypeptide chain.2. Because of this, movement of oxygen from maternal to fetal circulation is facilitated.3. One molecule of DPG is bound per hemoglobin tetramer, in its central cavity, in the T-form, when the space between the H-helices of the beta chains is just wide enough to accommodate it1. Carbon monoxide reversibly binds hemoglobin to one of the oxygen binding sites and conves the molecule into carboxyhemoglobin (CoHb). CoHb binds the three remaining sites to oxygen;2. However, the conformation of the molecule is such that it does not release the bound oxygen. The oxygen saturation of hemoglobin, therefore, remains normal, yet the oxygen cannot be off-loaded in peripheral tissues. For this reason, CoHb has the effect of shifting the oxygen dissociative curve to Left.3. Also, CO has 240 times more affinity for Hb than 02Refer: Textbook of Medical Biochemistry By S Ramakrishnan. Pg no: 102
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