Based on the following data, is the p50 higher or lower than normal in (a) hemoglobin Yakima and (b)hemoglobin Kansas? Explain.NameYakimaKansasMutationAsp G1 (99) ẞ → HisAsn G4 (102) ß → ThrEffectDisrupts a hydrogen bond that stabilizes theT conformationDisrupts a hydrogen bond that stabilizes theR conformation

P50 is defined as the oxygen tension at which haemoglobin is 50%saturated with oxygen .When…

Answered: Based on the following data, is the p50…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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In a molecular disease of hemoglobin, Hemoglobin Rainier, Tyr 145β is replaced by Cys, which forms a disulfide bond with another Cysresidue in the same subunit. This prevents the formation of ion pairs that normally stabilize the T state. How does hemoglobin Rainier differ from normal hemoglobin with respect to (A)oxygen affinity, (B)the Bohr effect, and (C)the Hillcoefficient? Explain your answers.
What qualitative effect would you expect each of the following to have onthe P50 of hemoglobin?(a) Increase in pH from 7.2 to 7.4(b) Increase in PCO2 from 20 to 40 mm Hg(c) Dissociation into monomer polypeptide chains(d) Decrease in 2,3-BPG concentration from 7 mM to 5 mM in red cells.
A variant of hemoglobin (Boston variant; mutation His E7(58)α → Tyr) promotes methemoglobin formation involving the α (alpha) subunits. What is the maximum value of the Hill constant (n) that you could measure for the Boston variant of hemoglobin? log (YO2 / 1 - YO2 ) = log pO2 - logP50 Please break down each step of the Hill equation and explain why the result for n is valid from a logical standpoint.
In a molecular disease of hemoglobin, Hemoglobin Rainier, Tyr 145β is replaced by Cys, which forms a disulfide bond with another Cysresidue in the same subunit. This prevents the formation of ion pairs that normally stabilize the T state. How does hemoglobin Rainier differ from normal hemoglobin with respect to the Hill coefficient
Suppose you mutate the proximal histidine of hemoglobin to glycine. You study the behavior of this mutant hemoglobin in the presence of 10 mM imidazole; the imidazole molecule can substitute for the proximal histidine chain and bind to the heme iron just as histidine does. a) Which state (T or R) will this mutation favor? b) Will oxygen binding to this state be tighter or weaker than oxygen binding to the same state of the wildtype hemoglobin? (note: wildtype means refers to the phenotype of the typical form of a species as it occurs in nature) c) Will this mutant still display significant cooperativity (Please provide clear and sufficient explanation for each part, thank you!)
Suppose you mutate the proximal histidine of hemoglobin to glycine. You study the behavior of this mutant hemoglobin in the presence of 10 mM imidazole; the imidazole molecule can substitute for the proximal histidine chain and bind to the heme iron just as histidine does. a) Which state (T or R) will this mutation favor? b) Will oxygen binding to this state be tighter or weaker than oxygen binding to the same state of the wildtype hemoglobin? (note: wildtype means refers to the phenotype of the typical form of a species as it occurs in nature) c) Will this mutant still display significant cooperativity?
In oxygenated hemoglobin, pKa 5 6.6 forthe histidines at position 146 on the -chain. In deoxygenated hemoglobin, the pKa of these residues is 8.2. How can this piece ofinformation be correlated with the Bohr effect?
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.
The figure below shows amino acid interactions between the a1/B2 subunit interface of hemoglobin. These interactions stabilize the T state of the protein. Based on the figure below, which amino acid in the picture below, if replaced with glutamate, would decrease the Kg of hemoglobin for O2 the most? Include both the residue and the residue number in your response (For example, V1 or K127). B, V34 8- a, R141 a2 D126 a, K127 Noncovalent Interactions
The mutation in hemoglobin at β82 Lys→Asp results in lowered O2-bindingaffinity compared to normal hemoglobin. β82 is one of the residues thatlines the 2,3-BPG binding site (as shown; β82 is adjacent to His 143). Based on the location of this residue and the differences between Lys and Asp, suggest a rationale for the observed reduction in O2-binding affinity.
Amino acid substitutions at the interfaces of the a and B subunits of hemoglobin can change the relative stability of the oxy (R) and deoxy (T) forms of the molecule. In one mutant hemoglobin molecule a hydrogen bond involved in stabilizing the R form of the molecule is lost. As a result, would expect this mutant hemoglobin to have a higher or lower affinity for oxygen as a ligand. Explain.
2,3-Bisphosphoglycerate lies in a central cavity within the hemoglobin tetramer, stabilizing the T state. What would be the effect of mutations that placed the BPG-binding site on the surface of hemoglobin?

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