The Bohr effect and the Haldane effect in human hemoglobin

Protons and carbon dioxide are physiological regulators for the oxygen affinity of hemoglobin. The heterotropic allosteric interaction between the non-heme ligands and oxygen, collectively called the Bohr effect, facilitates not only the transport of oxygen but also the exchange of carbon dioxide. Several types of interactions can be thermodynamically formulated. The Bohr and Haldane coefficients and the classical Bohr and Haldane coefficients are thus explicitly defined, which will save confusion about the use of the term "Bohr effect" seen in the literature. Molecular mechanism and the physiological significance of the classical Bohr and Haldane effects are outlined. The latter effect seems to play a far greater physiological role than the reciprocal influence of carbon dioxide on oxygen transport--the classical Bohr effect.