myoglobin-keyproperties(完整版)
【正文】 made to facilitate analysis of binding curves. Binding of O2 to the Heme Changes the Whole Structure of Hemoglobin b chains further apart Shifts at the ab interfaces R state T state The T to R State Transition ? Binding of O2 causes a series of shifts in all subunits ? Change in heme structure upon binding O2 ? Since His F8 is covalently attached, all of F helix shifts ? Reanization of helix alters tertiary structure, which in turn alters the quaternary structure 4 chains behave as a single cooperative structural unit ? Changes in packing of hydrophobic side chain ? Changes in pairing of charged side chains The change in conformation of Hemoglobin from the T to the R state increases O2 affinity at ALL sites Allosteric Effectors ? The R or T state can be stabilized by the binding of ligands other than O2. 1. H+. Lower pH favors the T state which causes Hb to release bound O2. This is known as the Bohr Effect. 2. CO2. Release of CO2 lowers pH via conversion to HCO3: CO2 + H2O ? HCO3 + H+. Reinforces Bohr Effect 3. Bisphosphoglycerate (BPG). Regulation of activity via binding more strongly to T state, helps to release O2. Increase in levels of BPG helps adaptation to high altitude faster than making more hemoglobin. Also important in hypoxia diseases (. anemia) HEMOGLOBIN at the pH (~) found in the lungs. HEMOGLOBIN at the pH (~) found in peripheral tissues. MYOGLOBIN in muscle (a peripheral tissue). Towards a More Complete Picture Model for disucssion Path of O2 Flow 1. O2 diffuses from the alveoli of the lungs into the capillaries of the bloodstream then into the red blood cells 2. In the red blood cells, O2 binds to hemoglobi
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1