And one fact about the T state is it's very unstable. So in the absence of the two three BPG molecule, there is a pocket, there is this space that is formed at the center of the deoxy hemoglobin. And inside that space, there is electrostatic repulsion that takes place between the amino acids on the beta one and the beta two subunits. So this is the hemoglobin, this is the beta one, beta two, and these are the alpha subunits. And if we examine at the corners of these two beta subunits, there are these residues that carry positive charges. And these positive charges basically repel one another.