Concept #1: BPG Effect on Oxygen Binding

Concept #2: BPG Only Affects Hb in the Tissues

Practice: Under which of the following conditions will hemoglobin bind less oxygen?

Concept #3: Physiological Regulation of [BPG]

Practice: In hemoglobin, the equilibrium transition from R state to T state is triggered by:

Practice: Some patients with erythrocytosis (excess red blood cells) have a mutation that converts a lysine to alanine at residue 82 in the β-subunit of hemoglobin. This particular lysine normally protrudes into the central cavity of deoxyhemoglobin, where it participates in binding 2,3-bisphosphoglycerate (BPG). Which of the following effects would you predict this mutation (Lys82Ala) to have on hemoglobin’s affinity for BPG and for O2 in patients with erythrocytosis?  Hint: The terms "increased" and "decreased" below are relative to normal (without mutation).

Practice: A 9-month old girl with hemolytic anemia is found to have a deficiency in the enzyme responsible for the conversion of molecule-B to pyruvate. Shown below is the oxygen saturation curve for hemoglobin in the erythrocytes of this patient (green curve), compared to the corresponding black curve in normal red blood cells. Which of the following is the most likely explanation for the observed oxygen saturation curve in this patient?

Practice: What is the effect of the following changes on the O 2 affinity of hemoglobin?

A) A drop in the pH of blood plasma from 7.4 to 7.2.

a) Lower the O2 Affinity.     b) Increase the O2 Affinity.


B) A decrease in the partial pressure of CO2 in the lungs from 6 kPa (holding one's breath) to 2 kPa (normal).

a) Lower the O2 Affinity.      b) Increase the O2 Affinity.


C) An increase in [BPG] from 5 mM (normal altitudes) to 8 mM (high altitudes).

a) Lower the O2 Affinity.     b) Increase the O2 Affinity.