t 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 O2 3) 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.

t 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 O2 3) 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.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter16: Human Genetics And The Human Genome

Section: Chapter Questions

Problem 6TYU

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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. < <
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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…
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