Bird hemoglobin are tetrameric and very similar in structure and function to mam
ID: 216654 • Letter: B
Question
Bird hemoglobin are tetrameric and very similar in structure and function to mammalian hemoglobins. However, in some bird species, O2 binding affinity to hemoglobin is not regulated by 2,3-BPG, but rather by a different compound that functions as a 2,3-BPG analog.
a) Considering the chemical and physical properties of the following compounds, which is the most likely candidate for the 2,3-BPG analog in bird red blood cells?
b) The bird 2,3-BPG analog binds to hemoglobin in the same way 2,3-BPG binds to mammalian hemoglobin. Briefly describe where in the structure of the tetrameric bird hemoglobin you would expect the compound to bind and by what type of bonds and/or interactions.
c) Would you expect the compound to increase or decrease the O2 binding affinity of bird hemoglobin?
OPO,2- ???? OPO,2 ?? ,N(CH3); 2o3PO HO ?? O3PO OPO 2 ?? OPO,2 ??Explanation / Answer
a) The second compound will act as 2,3-BPG analog.
b) In deoxygenated state, Hb binds one molecule of the compund in the central cavity formed by its four subunits. The compound forms salt bridges with the terminal amino groups of both beta chains. The compound thus stabilizes deoxygenated or T state of Hb by forming additional salt bridge.
c) It will decrease the oxygen affinity of bird Hb.
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