 There is an even cooler example of induced and selected fit. Remember how I promised you to tell you why myoglobin, hemoglobin, looks different. So myoglobin is the single domain that binds oxygen in our muscle tissue, while hemoglobin is the related protein that causes four roughly similar subunits that binds oxygen in our blood. I was actually lying a little bit there because there are two subunits of one type and two subunits of another type, which must be related to the function of one way or another. It turns out that myoglobin is a quite simple molecule why hemoglobin is complicated. Hemoglobin moves between at least two different states and that achieves something remarkably cool. I'll show you a short movie to illustrate how that works. Normally hemoglobin without oxygen present exists in something we call the deoxygenated or the tensed state. As one oxygen molecule starts to bind here, that will cause the entire molecule to shift over into a relaxed state that is actually better at binding oxygen. And that's strange because that behaves the opposite way of what molecules normally do. Normally I would expect to have a molecule like myoglobin in this plot. That is the first molecule I bind is really easy and then it gets harder and harder. Do you see how hemoglobin exhibits the opposite pattern? When the partial pressure of oxygen is quite high, that is in my lungs, it's going to be great at taking up extra oxygen. But as this has then been transported out to the muscle cells where the partial pressure of oxygen is low, then we're down here. It turns out that hemoglobin is then lousy at binding oxygen and it's going to release that oxygen to myoglobin in your muscles, which is exactly where I want it. So this leads to a remarkably efficient process and that's of course why nature has evolved this. This was first identified by Monod Weiman and Chageux at the Pasteur in the 1960s or 70s. And it's a fundamental concept called allosteric modulation that occurs throughout nature. And a simpler way of formulating it could be it's pretty much the way binding one small molecule can result in a much larger effect. So nature and proteins in particular are more or less working as transistors. So Monod Weiman and Chageux. Monod and Weiman are no longer around, but Champiain is actually still an active researcher at Pasteur and working in the same field as we are at Ligand Gate at Einstein. So it's great to have had a chance to interact with them.