Hemoglobin (Hb), the main oxygen carrier, is a tetramer in which each monomer (α1, α2, β1; and β2) contains a porphyrin prosthetic group. Initiated in 1937, the long path to understanding Hb biochemistry led to high-resolution X-ray Hb analysis (Perutz, 1968), which was a landmark achievement for the formulation of the '‘Perutz mechanism” based on the stereochemistry of the cooperative effects in Hb oxygenation [1], One of the most complex proteins, Hb is also the most studied over the last 30 years. Since oxygen exchange is controlled by the reversible steric configuration of the protein, Hb has been nominated as an “honorary enzyme” (Voet and Voet [2]).