Question

To study the chemical properties of the blood hemoglobin of a vertebrate, it might seem convenient to remove the hemoglobin from the red blood cells so that the hemoglobin is in simple aqueous solution. However, removing the hemoglobin from red blood cells often promptly alters its O2-binding characteristics. Why? The red blood cells typically contain metabolites that modulate hemoglobin function. A good example is provided by 2,3-DPG in mammals. In many cases, 2,3-DPG in the red blood cells causes the O2 affinity of the hemoglobin in the cells to be lower than it would otherwise be. If the hemoglobin is removed from the red blood cells, it is no longer exposed to 2,3-DPG, and the modulating influence of 2,3-DPG on O2 affinity is lost.

Answer 1

Red blood cells contain 2,3-DPG which modulates the O2 affinity of hemoglobin, causing it to be lower. Removing hemoglobin from red blood cells removes it from the influence of 2,3-DPG, leading to changes in O2-binding characteristics.