2. You have made a mutation in myoglobin that increased the Pso for O2 by a factor of 2. Sket- out an approximation of what the fraction of ligand bound sites vs partial pressure of oxygen plot would look like for this mutant as compared to the wild-type myoglobin (dotted line). Y 0.5 Po2

2. You have made a mutation in myoglobin that increased the Pso for O2 by a factor of 2. Sket- out an approximation of what the fraction of ligand bound sites vs partial pressure of oxygen plot would look like for this mutant as compared to the wild-type myoglobin (dotted line). Y 0.5 Po2

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter11: The Blood

Section: Chapter Questions

Problem 1SQE

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1. a. In active muscle cells, the pO2 is about 10 torr at the cell surface and 1 torr at the mitochondria(the organelles where oxidative metabolism occurs). Calculate the percentage of bound oxygentransported to the mitochondria of muscle cells by myoglobin (KD = 2 torr). b. A new oxygen transport protein that exhibits cooperative binding has been isolated and is beingstudied in the lab. Calculate the KD value if Y = 0.76 when pO2 = 18 torr (assume n = 2.5). Howdoes this compare to the KD value for hemoglobin? Does this protein bind more or less tightly tooxygen compared to hemoglobin?
2.(a) The two diagrams on the right compare O2 binding pro- perties of Hb Kariya, a human hemo- globin characterized by the mutation Lys(a40)Glu, with those of HbA as a function of pH ranging from pH 9.0 to pH 6.95. One O2 saturation curve () illustrates the O2 binding proper- ties at pH 7.5 in the presence of 2 mM inositol hexaphosphate (IHP). (IHP is found in avian red blood cells. and binds more tightly than BPG be- cause of the additional negative charges.) log [Y/(1 - Y)] Hb Kariya + IHP (b) The diagram on the right illustrates sche- matically the interaction of the side chain of the aLys40 residue with the C-terminal -COOH group of the B-sub- unit in HbA. In Hb Kariya with a Lys(a40)Glu mutation, which allosteric conformation R or T is destabilized, and which allosteric HbA conformation is illustrated on the right? Explain log (P) Excluding the O2 saturation curve collected in the presence of inositol-hexaphosphate (IHP), indicate with an arrow for both hemoglobins the plot…
1.1 ;) The diagram on the right compares the O2 binding prop- 1.0 erties or normal adult hemoglobin (HbA) to those of one dubbed Hb Great-Lakes characterized by the mutation Leu(B68)His. In the dia- gram Y = fraction of heme groups with bound O2, and pO2, the par- tial pressure of O2 above the solution, is measured in units of torr or mmHg. Hb Great Lakes %3D 0.8 Hb A 0.6 Draw the corresponding Hill plot, being careful to reproduce graph- ically the dissociation equilibrium constant for O2 binding (Ko2) for Y each hemoglobin and to show the difference in the extent of allo- stery or cooperativity of subunit interaction in each type of hemo- globin. 0.4 You need draw only the central, linear portion of the Hill plot. 0.2 F State what is the likely magnitude of the Hill constant (nH) for HbA from your reading and state what is the likely range of the magni- tude of the Hill coefficient for Hb Great Lakes. 0 10 20 30 40 50 60 pO2 (torr)
3. (a) The (acid) Bohr effect is defined as the up- take of protons by hemoglobin molecules at pH ≤ 6.5 as O2 is dissociated from the protein in solution. Approxi- mately 0.6 mole protons are taken up for each mole of O2 released by normal human hemoglobin. The effect is seen as a "shift to the right" in the O2 dissociation curves with decrease in pH, indicating that the O2 binding affinity of Hb decreases at lower pH. On the right is a diagram compar- ing the pH dependence of the p50 values of Hb Deer Lodge [His(32)Arg] (filled symbols) and of HbA (- - -) in the absence of organic phosphates, i.e., “Stripped”, and in the presence of saturating concentrations of IHP. On the basis of the definition of the Bohr effect given above, explain why the data in the diagram reflect the Bohr effect for the two types of human hemoglobins. log p50 1.5 1.0 0.5 0.0 -0.5 5 6 stripped 7 pH +DPG 8 IHP 9 (b) The Bohr effect is generally decreased in Hb Deer Louge compared to that in HbA. Provide an…
30. The cooperative binding behavior of hemoglobin for oxygen is best explained by... Group of answer choices The movement of the proximal histidine upon O2 binding causes a structural change at the binding interface between subunits The oxidation of Fe2+ to Fe3+ and formation of the superoxide ion causes distortion of the protoporphyrin ring, altering binding interface between subunits The tetrameric nature of hemoglobin's quaternary structure directly confers cooperative binding activity The movement of the distal histidine upon O2 binding causes a structural change at the binding interface between subunits The binding of O2 causes a pH shift that changes the protonation state of amino acids located at the interface between subunits The solubility of hemoglobin in aqueous solution and its insolubility in nonpolar environments
4. The diagram below illustrates time dependent O₂ uptake by isolated skeletal muscle mito- chondria under various conditions that affect the rate of respiration. The following abbreviations with arrows indicate when addition of various ingredients is made to the reaction chamber: The vertical, red lines have been added to help delineate time intervals corresponding to addition and metabolic con- version of ADP. Abbreviations: Med addition of 0.3 M sucrose; Pi: addition of 0.01 M phosphate buffer, pH 7.4; Mw: addition of isolated, intact mitochondria; Pyr + Mal: addition of 0.01 M pyruvate + 0.01 M malate; ADP : addition of adenosine 5'-diphosphate; Oligo/mg: addition of oligomycin/mg protein; FCCP : addition of the uncoupler FCCP. Med Pyr+Mal P₁ 190μM ADP ↓ 20μM 02 T H 190μM ADP I Minute 475μM ADP 2μM FCCP 13μg Oligo/mg -[0₂] = 0 ATP [ATP] = 0 ApH = (pH matrix -pHout) ApH = 0 Start Finish (a) Why is there an increase in the rate of O2 uptake for the first two additions of ADP and why…
2. The two diagrams to the right il- lustrate plots of steady-state ki- netic studies to characterize the in- teraction of heart muscle phos- phofructokinase-1 with a non-phy- siological, synthetic substrate fruc- tose-6-sulfate. Because the kcat is smaller than that for the natural 5 0.8- NH = 3.5 0.6- 0.4- 0.2- 10 μΜ 20 μΜ 48 µM substrate, higher enzyme concen- trations could be used. The results show the influence of increasing 2 0.2- 0.4- concentrations of ATP on the initial -0.6- > velocity of the enzyme catalyzed reaction in the presence of no -0.8F 4 12 20 28 36 44 52 60 68 76 84 92 .2 2.0 2.4 ΑMP () , 10 μΜ AMP (+ ) 20 μΜ AMP (-), and 48 µM AMP (-). [AΤP] (μΜ) log[ATP] (µM) (a) . Write the reaction in words catalyzed by the enzyme for the alternative substrate, describe how ATP interacts with the enzyme in the case of no AMP (•). (b) ! with respect to the binding of AMP and ATP to the allosteric effector sites on the enzyme. Explain the physical significance of the displacement…
O2-binding curves 1 0.9 0.8 2 0.7 3 0.6 0.5 0.4 0.3 0.2 0.1 100 120 20 40 60 80 po2 (torr) Fractional Saturation
You have discovered a new form of mouse myoglobin that has a p50 of 9 Torr. At approximately what pO2 would this hemoglobin be 86% saturated with oxygen? 85 Torr 40 Torr 60 Torr 55 Torr Not enough information is given to answer this question
In one type of hemoglobin mutant the amino acid change generates a strong ionic interaction stabilizing the T state conformation, but only under conditions of lower pH, e.g., at pH 7.2 compared to pH 7.6. Explain what effect this mutation would have on the amount of O2 delivered to the tissue. More O2 delivered to the tissue because the R-T equilibrium would be shifted to the T state in tissues. More O₂ delivered to the tissue because the R-T equilibrium would be shifted to the T state in lungs. Less O2 delivered to the tissue because the R-T equilibrium would be shifted to the T state in lungs. Less O₂ delivered to the tissue because the R-T equilibrium would be shifted to the T state in tissues. More O2 delivered to the tissue because the R-T equilibrium would be shifted to the R state in tissues.
1. What are two features of Viperin-like enzyme structure that make it different OR similar to haemoglobin? 2. Based on the structural properties of Viperin-like enzyme, how resistant (or sensitive) would your Viperin-like enzyme be to heat denaturation and why?
A new oxygen transport protein that exhibits cooperative binding has been isolated and is beingstudied in the lab. Calculate the KD value if Y = 0.76 when pO2 = 18 torr (assume n = 2.5). Howdoes this compare to the KD value for hemoglobin? Does this protein bind more or less tightly tooxygen compared to hemoglobin?