2,3-BPG is a molecule found in red blood cells that plays a crucial role in regulating oxygen binding and release by hemoglobin. Here's an overview:
Role of 2,3-BPG :-
• Binding to hemoglobin: 2,3-BPG binds to the beta chains of deoxygenated hemoglobin (deoxyhemoglobin) in the central cavity between the two beta subunits. This binding stabilizes the T (tense) state of hemoglobin.
• Decreasing oxygen affinity: By stabilizing the T state, 2,3-BPG reduces hemoglobin’s affinity for oxygen. This means that in the presence of 2,3-BPG, hemoglobin is more likely to release oxygen to the tissues.
|
Shift Direction |
Factor |
Effect on oxygen affinity |
Physiological implications |
|
Right shift |
1. Increased CO₂ (Hypercapnia) 2. Increased H⁺ (Decreased pH, acidosis) 3. Increased temperature 4. Increased 2,3-BPG 5. Exercise |
Decreased |
Enhanced oxygen |
|
Left shift |
1. Decreased CO₂ (Hypocapnia) 2. Decreased H⁺ (Increased pH, alkalosis) 3. Decreased temperature 4. Decreased 2,3-BPG 5. Presence of fetal hemoglobin (HbF) |
Increased |
Reduced oxygen |
|
Factor |
Effect on Oxyhemoglobin |
Shift Direction |
|
2,3-BPG |
Decreases hemoglobin's |
Right Shift |
|
2,3-BPG |
Increases hemoglobin's |
Left Shift |
• Rightward shift of the oxygen dissociation curve: The presence of 2,3-BPG causes a rightward shift in the oxygen dissociation curve. This indicates that a higher partial pressure of oxygen (pO2) is required to achieve the same level of hemoglobin saturation compared to when 2,3-BPG is absent.
Oxygen Affinity :-
• High affinity state (R state): In the lungs, where the oxygen concentration is high, hemoglobin binds oxygen tightly, favoring the R (relaxed) state.
• Low affinity state (T state): In the tissues, where oxygen concentration is lower, hemoglobin releases oxygen more readily, favoring the T state. 2,3-BPG facilitates this release by binding to hemoglobin and promoting the T state.
Physiological Importance: This regulation ensures efficient oxygen uptake in the lungs and delivery to the tissues. Without 2,3-BPG, hemoglobin would hold onto oxygen too tightly, impairing oxygen delivery.