Bohr effect, hemoglobin structure

Hemoglobin s dioxygen binding is regulated by local concentrations of H+ (known as the Bohr effect), CO2 concentration, and organic phosphates such as diphosphoglycerate (DPG), whose structure is shown in Figure 4.2.17... 

The transition between the T and R states of hemoglobin is also deeply involved in the Bohr effect and cooperativity. Therefore stabilization of either of the two structures should diminish these effects, which have important physiologic consequences. The clinical consequences of stabilization are... 

The most important and universal type of chemical equilibria to which a heme protein is subjected in natural environments is pH equilibria, involving the protein aminoacid residues and the ionizable groups of the porphyrin, the propionate side chains. Beside the effects on the overall protein structure, which are outside the scope of this review, the major consequences of proton equilibria may be the changes of the heme reduction potential (electron affinity), called the redox-Bohr effect (see Sect. 3.2), by analogy to the pH effect on the oxygen affinity of hemoglobin (Bohr effect). 

When such an amino acid is incorporated into a protein, the local chemical environment in the protein may affect the pK of a group and thus alter its charge. Such changes can be very important in the function of proteins (e.g., the Bohr effect in hemoglobin depends on structural changes that affect the pK of histidine... 

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