Well, that's because when our molecule goes from the 10th state, the deoxyhemoglobin state to the relaxed state, that oxymoglobin state, the two alpha beta dimers rotate 15 degrees with respect to one another. And this rotation is what causes this cooperative behavior of that hemoglobin molecule. This rotation is what causes that shift to take place from the 10th state to that relaxed state. So when hemoglobin is oxygenated, one of the AlphaBeta dimers rotates 15 degrees with respect to the second AlphaBeta dimer. And this shift leads to the cooperative behavior of hemoglobin. So we conclude that when we have the deoxyhemoglobin and one of the unoccupied heme groups begins to bind an oxygen molecule, it induces a conformational change from the t state to that relaxed state.