1. The T conformation of hemoglobin is stabilized (in part) by a hydrogen bonding interaction between the negatively-charged carboxylate group of the side chain of Asp99 in the β-subunit of one αβ dimer and the -OH group of the side chain of Tyr42 in the α-subunit of the opposing αβ dimer. Draw a diagram of this hydrogen bonding interaction (show complete side chains). 2. In an abnormal hemoglobin variant known as Hemoglobin-Radcliffe, the Asp99 residues in the β-subunits are replaced by alanine residues. This change eliminates the hydrogen bonding interaction that normally occurs between Asp99 in the β-subunit of one αβ dimer and Tyr42 in the α-subunit of the opposing αβ dimer. a) What effect would you expect this change to have on the quaternary structure and oxygen binding properties of hemoglobin? (see question 1) b) Draw a diagram to illustrate the difference in the oxygen binding curves that would be obtained with normal hemoglobin and Hemoglobin-Radcliffe.
1. The T conformation of hemoglobin is stabilized (in part) by a hydrogen bonding interaction between the negatively-charged carboxylate group of the side chain of Asp99 in the β-subunit of one αβ dimer and the -OH group of the side chain of Tyr42 in the α-subunit of the opposing αβ dimer. Draw a diagram of this hydrogen bonding interaction (show complete side chains).
2. In an abnormal hemoglobin variant known as Hemoglobin-Radcliffe, the Asp99 residues in the β-subunits are replaced by alanine residues. This change eliminates the hydrogen bonding interaction that normally occurs between Asp99 in the β-subunit of one αβ dimer and Tyr42 in the α-subunit of the opposing αβ dimer.
a) What effect would you expect this change to have on the quaternary
structure and oxygen binding properties of hemoglobin? (see question 1)
b) Draw a diagram to illustrate the difference in the oxygen binding curves that
would be obtained with normal hemoglobin and Hemoglobin-Radcliffe.
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