What is the function of 2,3-bisphosphoglycerate in relation to hemoglobin?

• A. Increase O2 affinity
• B. Decrease O2 affinity
• C. No effect on O2 binding
• D. Bind directly with CO2

Answer: (B)

2,3-bisphosphoglycerate (2,3-BPG) plays a significant role in regulating the affinity of hemoglobin for oxygen. In the presence of increased 2,3-BPG levels, hemoglobin's affinity for oxygen decreases. This reduction in affinity facilitates the release of oxygen from hemoglobin in tissues where it is most needed, particularly during states of high metabolic activity.

When 2,3-BPG binds to deoxygenated hemoglobin, it stabilizes the tense (T) state of the hemoglobin molecule, promoting the release of oxygen. This is particularly important in conditions such as anemia or high altitudes, where oxygen delivery becomes critical. The ability of 2,3-BPG to modulate hemoglobin's affinity for oxygen is an essential aspect of the physiological response to varying oxygen demands within the body.

Understanding this mechanism is crucial for grasping how hemoglobin functions under different physiological conditions and how it influences oxygen transport and delivery in various tissues.