Oxygen binding hemoglobin

We can determine quantitatively the physiological significance of the sigmoid nature of the hemoglobin oxygen-binding curve, or, in other words, the biological importance of cooperativity. The equation... 

Two quite different models were proposed about 25 years ago to explain the unusual nature of the hemoglobin oxygen-binding curve (fig. 5.14). These models can also be used as a starting point for discussing other allosteric proteins. The first model, introduced by Jacque Monod, Jeffery Wyman, and Pierre Changeux in 1965, is called the symme-... 

Oxygen and H are not bound at the same sites in hemoglobin. Oxygen binds to the iron atoms of the hemes, whereas H binds to any of several amino acid residues in the protein. A major contribution to the Bohr effect is made by His (His HC3) of the 3 subunits. When protonated, this residue forms one of the ion pairs—to Asp (Asp FGl)—that helps stabilize deoxyhemoglobin in the T state (Fig. 5-9). The ion pair stabilizes the protonated form of His HC3, giving this residue an abnormally high piCa in the T state. The falls to its normal value of 6.0 in the R state because the ion pair cannot form, and this residue is largely unpro-... 

HEMOGLOBIN OXYGEN BINDING, ERYTHROCYTE SHAPE TRANSFORMATIONS, AND MODELING OF CELL DIFFERENTIATION AS EXAMPLES OF THEORETICAL APPROACHES IN STUDYING THE STRUCTURE-FUNCTION RELATIONSHIP IN BIOLOGICAL SYSTEMS... 

Fig. 1.1. (a) Fraction of occupied oxygen binding sites in hemoglobin and in a separated subunit as a function of partial oxygen pressure. The hemoglobin oxygen binding curve is... 

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