Hemoglobin square model

Figure 9 Two proposed models for allosteric interaction observed in hemoglobin, (a) A sequential model of allosteric interaction. When one O2 molecule binds to a subunit in the T-state, the subunit shifts to R-state and affects the affinity of neighboring subunits for the ligand binding, (b) An MWC two-state concerted model of allosteric interaction. When one O2 molecule binds to a subunit in all T-states, a concerted conformational change occurs to produce a protein with all R-state subimits. Square and circle represent T- and R-state subunits, respectively. Moreover, opened and closed diagrams represent free and O2 bound subunits, respectively...

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