The oxygen-binding curves for nomral hemoglobin (HbA) and a mutant hemoglobin (H

Question

The oxygen-binding curves for nomral hemoglobin (HbA) and a mutant hemoglobin (Hb Great Lakes) are shown in the figure above.

(a) Compare the shapes of the curves for the two hemoglobins and comment on their significance.
(b) Which hemoglobin has a higher affinity for oxygen when pO2 = 20 torr? (1 torr = 1 mm Hg; 1 atm = 760 mmHg or 760 torr)

(c) Which hemoglobin has a higher affinity for oxygen at pO2 = 75 torr?
(d) Which hemoglobin is most efficient at delivering oxygen from arterial blood (pO2 = 75 torr) to active muscle (pO2 = 20 torr)?

Explanation / Answer

Answer

a. HbA - sigmoidal, means it binds oxygen at a linear rate over a pressure range. Hb-GL - parabolic, means its rate of oxygen binding decreases with increasing pressure.

b. At 20 torr, Hb GL has higher affinity

c. At 75 torr, both HbA and Hb GL has same affinity and reaches the saturation level

d. HbA, because it has less binding affinity at 20 torr.

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