Justify all answers (show all work).1. Minor changes in primary structure can have pronounced effects on biological function. Tetramerichemoglobin, a₂³₂, dissociates into pairs of dimers aß to different extents depending on the protein primarystructure. The standard Gibb energies of dissociation of normal adult hemoglobin A and of several mutantshave been determined and are listed in the table below.Substitution in mutantHemoglobinA, normalRichmondKansasGeorgia102B; Asn → Thr102B; Asn → Thr95x; Pro → LeuAG® of dissociation (kcal/mole Hb)8.26.0655.13.6(a) Write an equilibrium expression for the dissociation of hemoglobin tetramer into dimers.(b) For normal hemoglobin and its three mutants (variations) calculate the equilibrium constant for theirdissociation from a tetramer into dimers.(c) How do the equilibrium constants for the dissociation of the hemoglobin mutants compare to that ofnormal hemoglobin?

Hemoglobin is a tertameric protein made up of 4 subunits namely α2β2. The αβ form a dimer and 2 such…

Answered: 1. Minor changes in primary structure…

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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2. Consider the coil-helix transition in a polypeptide chain. Let s be the relative weight for an H after an H, and as the relative weight for an H after a C. H and C refer to monomers in the helical or coil states, respectively. These equations may be useful: Z3 = 1+ 30s + 2os² + o²s² + σs³ Obtain the probability of 2 H's for the trimer case. Why is a <<<1? b)
A mixture of five proteins are analyzed by MALDI-TOF. Their molecular weigths are 3 kD, 22 kD, 100 kD, 225 kD and 515 kD. A peak appears in the mass spectrum at 33.3 kD. Which protein most likely gave this peak?
(a) 1 Normalized fluorescence 0.8 0.6 0.4 0.2 0 1.7.0- 50 55 OM 0.100 M 0.200 M 0.300 M 0.500 M 1.00 M 2.00 M Where is fully folded protein? • Where is fully unfolded protein? • Where is partially folded protein? 60 A 65 Temp. (°C) 70 75 80 To what does SYPRO orange bind? • Why does fluorescence increase as a function of temperature? • Define a melting temperature for a protein. • Demonstrate how an estimated melting temperature of the protein in zero molar ligand can be determined. • What is the effect of increasing the molar concentration on melting temperature for this protein? Why is melting temperature a useful measurement to make for a protein especially if you are interested in protein aggregation?
You have discovered a new hemoglobin variant you are calling Hb-21. You have noticed the following from your studies of Hb-21: - The binding constant of Hb-21 is the same at pH 7.1 and 7.4.- The binding constant curves generated by Hb-21 and O2 are sigmoidal.- The Hill coefficient for Hb-21 is 3.-The binding constant for Hb-21 with O2 in the presence of 5mM 2,3-bisphosphglycerate is about 6-times lower instead of the 8-times lower that is observed under these conditions for the wild type enzyme. Use this information to answer questions: Based on this information which of these features of hemoglobin would you conclude are altered in Hb-21 as compared to the wild type hemoglobin? ____ the cooperativity.____ the amount of T versus R state in the tissues. ____ the Bohr effect. What is the major issue for an individual with the Hb-21 variant? Explain exactly what aspect of hemoglobin’s function is altered.
1. Amino Acid 1 = W + X = 1 Draw amino acid 1 at a low pH a) As the D Fisher Projection Name of amino acid 1: b) As the S isomer: Arginine
2. (6) Examine the two proteins labelled a) and b). Which of the two Ramachandran plots, c) or d) is more likely to be derived from which protein? Explain how you determined this. (a) (b) (c) (d) ✓ (degrees) ✓ (degrees) +-180 120 60 -60 -120 -180 -180 +180 120 60 -120 -180 -180 0 (degrees) 0 (degrees) +180 +180
You have discovered a novel protein that has a pl = 5.5. To study the functional properties of this new protein, your research group has made a mutant that contains two amino acid changes: a surface phenylalanine residue in the normal protein has been replaced by histidine (side chain pK, = 6.1), and a surface glutamine has been replaced by glutamic acid (side chain pK, = 6.0). Is the pl of the mutant protein predicted to be greater than, less than, or the same as the pI of normal protein? Support your answer with the appropriate calculation.
Which positions can tolerate conservative substitution?
a and b please
2. It is known hemoglobinopathies, whi ch arise due to mutations in one of histidines a- or B- chains binding with the iron in the heme gro up.These mutations stabilize the iron in Fes form. Some drugs (eg. sulfonamides) or chemicals( eg.anilin) also can cause methemoglobinemia. Suggest, how change the properties of Hb in these cas es. For this:1)Describe the structure and function of Hb A as a transport protein. 2) Explain the role ofiron ions in act ive centers of Hb for the binding of O23) How many molecules of Oz can bind mutant Hb, if mutation occurs in a- subunits? 4) Why can ascorbic acid be used to tr eat of such patients.
5. Anesthetic gases used in surgery are known to bind to the hemoglobin molecule in red blood cells. The diagram below illustrates O2 binding curves of normal human HbA in the presence of the anesthetic gas dichloromethane (DCM). O UNTREATED 100 Symbols: a Dсм 23 Torr • DCM 50 Torr x DCM I00 Torr o, 0 Torr DCM; О, 23 Torr DСМ Д, 50 Torr DСМ x, 100 Torr DCM. 80 60 40 (1 Torr = 1 mm Hg.) 20 The solutions were buffered to pH 7.4. 0.5 1.0 1.5 2.0 log p02 For the curves at 0 and 100 Torr of dichloromethane, draw their equivalent in the form of (a) (* Hill plots. Label the axes and indicate on both the plot above and the Hill plot where the value of the dissociation equilibrium constant Kd for O2 binding is defined for 0 and 100 Torr of dichloromethane Kd Hb(O2)n nO2 Hb + Be sure to label the axes, indicate the units on both axes, and make the Hill plot so that the values of Kd are equivalent to those on the saturation plot above. Indicate whether cooperativity, as indicated by the Hill…
1) Describe one inner and one outer approach for the prediction of contact or distance maps in proteins.

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