Abstract
Normal and Abnormal Protein Subunit Interactions in Hemoglobins
Highlights
All stages of interactions between subunits in the assembly process and their reciprocal dissociations are in continuous and rapid equilibrium as shown in Equation 1
We focus first on how subunit interactions between the two dimer pairs result in formation of the central cavity, which is involved in the binding of some allosteric regulators to one state but not the other
We consider the details of aggregation of tetramers into polymers of sickle hemoglobin (HbS), (␣22)n in one state but not the other, and we describe an example of the complete dissociation of tetramers to monomers in fish hemoglobin, which is unlike human hemoglobin where dissociation essentially stops at the dimer
Summary
These subunit interactions control the binding of allosteric regulatory molecules because of sites they create as they interact with one another Some of these interactions in hemoglobin change in the transition between its tetrameric oxy (R, for “relaxed”) or deoxy (T, for “tense”) conformational states; adult human hemoglobin A (␣22) functions as the physiological carrier of O2 between the arterial and the venous circulation in these two conformations, respectively. All stages of interactions between subunits in the assembly process (known as association) and their reciprocal dissociations are in continuous and rapid equilibrium as shown in Equation 1 In this minireview, we focus first on how subunit interactions between the two dimer pairs result in formation of the central cavity ( referred to as the crystallographic dyad axis), which is involved in the binding of some allosteric regulators to one state but not the other.
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