So once again, the T state of hemoglobin in its pure form is highly unstable because it contains a pocket with positive charges at the center of that tetrimer where the positive charges come from these six amino acids found on these opposing beta subunits. So this instability pushes the equilibrium towards the R state, towards the right side. And physiologically, what this means is pure hemoglobin, in the absence of two three BPG would bind oxygen way too strongly with a very high affinity because it would exist predominantly in the R state. And that's precisely why the curve is found towards the left side with respect to the blue curve because as we shift the curve towards the left side, that increases the affinity of that molecule hemoglobin towards oxygen. Now, in our red blood cells, we have this molecule, 23 BPG that can bind into that pocket because it's a small enough, and b contains the negative charges. And by interacting with the positive charges, we decrease the overall charge in that center area, and that stabilizes the t state of the deoxy hemoglobin and drives the equilibrium back towards the t state.