Hemoglobin carries oxygen gas in the body. It consists of four sections, with each section being able to carry one molecule of oxygen gas. The equation for the reversible reaction for the oxygenation/deoxygenation of hemoglobin is given below:
Hb + 4 O2 ⇌ Hb·4 O2
The Hb in the equation represents hemoglobin. The dot with the 4 O2 means that the 4 O2 molecules are associated with the hemoglobin, not part of the molecule. The same is true for the dot followed by 2 H+ (remember from Chapters 3 and 5 that H+ is characteristic of an acid).
Discuss the reaction in regard to its equilibrium and the factors that contribute to oxygenation/deoxygenation of hemoglobin. Consider the effects of the concentration of O2 and the effects of the concentration of H+ on the degree of oxygenation of hemoglobin. In the lungs, the concentration of O2 is high, while in the tissues, the concentration of O2 is low. The opposite is true for the concentration of H+. What does this imply about the direction of the reaction in the lungs as opposed to the reactions in the peripheral tissues? Under which conditions, acidic or normal body conditions, would you expect O2 to bind more strongly to hemoglobin?