What is the effect of 2,3-BPG on hemoglobin oxygen affinity?

• A. It decreases affinity, promoting oxygen unloading
• B. It increases affinity, hindering unloading
• C. It has no effect on affinity
• D. It binds CO2 instead of O2

Answer: (A)

2,3-BPG binds to the deoxygenated form of hemoglobin and stabilizes the T (tense) state, which decreases hemoglobin’s affinity for oxygen. This shifts the oxygen dissociation curve to the right, so at a given partial pressure of oxygen, hemoglobin releases more O2 to tissues. This helps with oxygen delivery, especially under conditions like hypoxia or high altitude when tissues need more O2. 2,3-BPG does not increase affinity, it does have a notable effect on binding, and it isn’t the molecule that carries CO2 in place of O2.