Hemoglobin deoxygenated states

In a review, Nocek et al discuss the use of proton pseudocontact chemical shift data to analyse structural perturbations in proteins that are too large for solution structure determination. The discussion focuses on oxygenated and deoxygenated states of hemoglobin. 

A Small Difference in the Geometry of the Heme Binding Site in the Oxygenated and Deoxygenated States of Myoglobin and Hemoglobin... 

The allosteric effect is seen in hemoglobin which can exist in two quaternary stmctural states oxygenated (R) or deoxygenated (T). The binding of one O2 or some other effector to one of the subunits stabilizes the R form as compared to the T form. Binding of a second and third O2 stabilizes it even further. 

Figure 38-4. Examples of three types of missense mutations resulting in abnormal hemoglobin chains. The amino acid alterations and possible alterations in the respective codons are indicated. The hemoglobin Hikari p-chain mutation has apparently normal physiologic properties but is electrophoretically altered. Hemoglobin S has a p-chain mutation and partial function hemoglobin S binds oxygen but precipitates when deoxygenated. Hemoglobin M Boston, an a-chain mutation, permits the oxidation of the heme ferrous iron to the ferric state and so will not bind oxygen at all.

State the major structural differences between the oxygenated and deoxygenated forms of hemoglobin. 

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