Oxygen hemoglobin dissociation curve.
H+ and 2,3-DPG compete with O2 for binding, so an increase in H+ (acidic pH) and 2,3-BPG concentration leads to reduced affinity. This shifts the curve to right. This is helpful at peripheral tissue to extract more oxygen.
An increase in temperature also shifts the curve to the right.
When the curve is shifted in the right direction, a higher PO2 is required for hemoglobin to bind a given amount of O2.
Curve shifts to left with a fall in temperature and decrease in 2, 3 DPG and increase in pH, When this happens oxygen can easily bind to hemoglobin.
|2, 3 DPG||shift to right||shift to left|
|Temperature||shift to right||shift to left|
|H+||shift to right||shift to left|
|pH||shift to left||shift to right|
The decrease in O2 affinity of hemoglobin when the pH of blood falls is called the Bohr effect.
When PCO2 raises pH of the blood decreases and curve shifts to right.
2, 3 DPG
2,3-DPG is present in red blood cells in plenty. It is formed from 3- phosphoglyceraldehyde,
This is a product of glycolysis via the Embden– Meyerhof pathway.
It is a highly charged anion that binds to the β chains of deoxyhemoglobin. One mole of deoxyhemoglobin binds 1 mol of 2,3-DPG.
An increase in 2,3 DPG competes with Oxygen thus liberating Oxygen.
With acidosis, glycolysis is inhibited and production of 2,3 DPG is reduced.
Thyroid hormones, growth hormones, and androgens can all increase the concentration of 2,3-DPG.
Exercise increases 2,3 DPG.