In acve muscle cells oxygen is rapidly consumed and

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Unformatted text preview: n binding of O2 in lungs? Effect of BPG on delivery (release) of O2 in .ssues? θ BPG concentra.on is the same in erythrocytes in lungs and in .ssues. BPG effect is much more pronounced at lower pO2 (in .ssues) since Hb is close to saturated with O2 in lungs with or without BPG. Berg, Tymoczko & Stryer, Biochemistry, 6th ed., Fig. 7 ­15 Some animals have different nega;ve heterotropic effectors •  Humans: 2,3 ­BPG •  Some other mammals (cats, ca]le, sheep)  ­ ­ Hb has low enough O2 affinity, don’t need 2,3 ­BPG. •  Birds: inositol hexaphosphate (IHP) or inositol penta ­ phosphate (IPP) •  Fish and most amphibians: ATP •  All bind in central cavity and reduce O2 affinity by stabilizing T state (deoxy conforma;on). Human high al;tude adapta;on: a complex physiological process Increase in number of erythrocytes (takes several days) Increase in amount of Hb per erythrocyte (may take several weeks) Increase in concentra.on of 2,3 ­BPG in erythrocytes Rapid short ­term adapta.on (< 24 hr) 3 2 1 Increased BPG Contributes to Al;tude Adapta;on Increase in 2,3 ­BPG from 5 mM (sea level conc.) to 8 mM decreases O2 affinity but increases high al.tude “delivery load” • Lehn. Principles, Fig. 5 ­17 The Bohr Effect Proton (H+) binding and CO2 binding reduce affinity of Hb for O2. Carbon dioxide and H+ ions also are effectors of hemoglobin. In muscle cells, oxygen is rapidly consumed and carbon dioxide and H+ ions are produced. Oxygen affinity decreases at lower pH. As hemoglobin moves into a .ssue with lower pH, it can more easily unload oxygen. Increase in carbon dioxide concentra.ons have...
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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