6. As the pH of its surrounding environment decreases from 7.4 to 7.0, protonation of particularin hemoglobin allows the formation of salt bridges that stabilize thequaternary structure, resulting inA. Fe2*; R; increasedB. Asp; T; decreasedC. Fe2*; T; increasedD. His; R; increasedE. His; T; decreasedstate of theoxygen-binding affinity.

Oxygen competitively and cooperatively binds to hemoglobin. This binding changes with certain…

Answered: 6. As the pH of its surrounding…

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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Which of the following statements is false concerning the structure of hemoglobin? a. The binding of BPG stabilizes the T-state of Hb b. The R-state of Hb is favored under environments of high concentrations of O2 c. Hemoglobin's affinity for oxygen increases as protons ionize from the N-terminal tails d. Hemoglobin is stabilized in the low affinity state in the presence of high concentration of protons e. Hemoglobin favors the R-state in basic environments
. In the experiments of Barrick, et al. ( observed that replacement of histidine by a noncovalently bonded imidazole not only reduced cooperativity but also increased the oxy- gen affinity of the hemoglobin. Suggest an explanation. it was
The O2-binding curve for Hemoglobin (Hb) is sigmoidal because: a O2 binding to Hb increases the binding affinity of Hb for additional O2. b The pH of blood is near the pKa of histidine. c The pH of the bloodstream changes with changes in O2 concentration. d Hb’s O2-binding affinity changes with changes in pH.
The figure shows interaction of various amino acids (Phe, Arg, and Asn) present in Hb with 2,3-DPG. The side chains of these amino acids and 2,3-DPG interactions are circled in red. HO Но Phe HN Asn H2N NH Arg You identify a mutant version of the globin chain where the Arg in circle 2 is replaced with aspartic acid in a patient. Would the Hb protein in this patient be able to transport oxygen even in the presence of 2,3-DPG? ASPARTIC ACID (asp) No, because the mutant Hb version will bind 2,3 DPG, and not oxygen Yes, because the mutant Hb version will bind 2,3 DPG, and not oxygen Yes, because the mutant Hb version will bind oxygen and not 2,3 DPG
2. (a) The binding site of 2,3-bisphosphoglycerate (BPG) (red stick figure) in the deoxyhemo- globin molecule is illustrated below. Note that the two phosphate groups and the carboxylate group of the BPG molecule confer strong, negative electrostatic character to the molecule. B₁-subunit 1. 2. 3. 5. 6. B₁ (b) Mutant Hemoglobin Hb Raleigh Hb Helsinki The mutant hemoglobins listed below each have a mutant amino acid in the ß-subunit directly in or in the vicinity of the BPG binding site. Rank the affinity of the following mutant hemoglobins for binding BPG (red stick figure above).. Explain your reasoning. The notation, for instance, as given for Hb Raleigh Val(31)Ala means that Val-1, the first amino acid residue of the ß-subunit, has been substituted by Ala. Hb Rahere Hb Rancho Mirage Hb Little Rock B₂ Hb Ohio Mutation Val (31)Ala Lys(382) Met Lys(382)) Thr His(143)Asp His(3143)Gln a-NHẠ Ala(142)Asp His 2 His 143 BPG His 143 Lys 82 His 2 Rank the affinity of the mutant hemoglobins for…
The steps involved in the T→ R transition in when oxygen binds to hemoglobin are outlined below. Place them in the correct order (1 = first thing to happen), assuming that it is the oxygen-binding that initiates the transition and that the process occurs in discrete steps. The proximal histidine is pulled by the heme iron. The F helix is pulled out of place, breaking a network of salt bridges. The iron is pulled into the plane of the protoporphyrin IX ring. Oxygen binds to the heme. < <
Which of the following statement(s) is/are FALSE for hemoglobin? A Demonstrates positive cooperativity and can bind up to four O2 molecule. B It exhibits the 4 levels of protein structure. C It is a trimer with 2 α-helices and 1 β-sheet. D It is an allosteric protein.
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
Apohemoglobin (apoHb) is a dimeric globular protein with two vacant heme‐binding. The preparationof apoHb is based on partial hemoglobin (Hb) unfolding to facilitate heme extraction into an organic solvent. What is an appropriate method for removing the heme? a. An acidic buffer to protonate the His axial ligand in the presence of ureaas the denaturing agent. b. An acidic buffer to protonate the His axial ligand in the presence of mercatoethanol as the denaturing agent. c. A basic buffer to deprotonate the His axial ligand in the presence of ureaas the denaturing agent. d. An basic buffer to protonate the His axial ligand in the presence of mercatoethanol as the denaturing agent.
Allosteric inhibitors of hemoglobin will decrease enzyme activity (oxygen binding) through which of the following mechanisms? Binding the enzyme in "T" conformation and displacing an activator Binding the enzyme and enhancing the Vmax Binding the enzyme, and keeping it in the "R" conformation Binding the enzyme, and keeping it in the "T" conformation
1. The human hemoglobin molecule, like all mammalian he- moglobins, is comprised of two a-chains and two ß-chains con- ₂ taining 141 and 146 amino acid residues, respectively. Be- cause the molecule possesses two-fold symmetry, there are a1-a2, B1-B2, and a1-B2 interfaces formed by amino acid sidechains through which structural changes are transmitted underlying ligand binding. The most important of these is the a1-B2 interface that is illustrated in the diagram on the right. All of the sidechain interactions across the a1-B2 interface are hydrophobic except for that between Asp(a94) and Asn- (B102). This is the only polar interaction across the α1-³2 in- terface and it helps to stabilize the oxy- or R-conformation. Its approximate location in the Hb molecule is represented by the red double arrow in the diagram on the right. His FG4 97 Asp G1 (99) Tyr C7 (42) Hb mutant (a) T State (deoxy) 95 The C6 41 (a) The diagram below on the right-hand side illustrates the polar Asp(a94). . . Asn…
Please fill in the following blanks with the options that correctly finishes the sentence. a. At a low O₂ pressure the [Select] hemoglobin is in a [Select] [Select] [Select] 9 [Select] " bond with [Select] heme, and the protein's central channel is [Select] b. The proximal histidine forms a(n) [Select] state is stabilized. In this conformation state, the heme prosthetic groups is each subunit's heme is more likely to be the proximal histidine is [Select ] bond with while the distal histidine forms a(n) [Select] to the

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