Enzymes Lower Activation Energy

Jason Amores Sumpter
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So now that we've introduced the activation energy in our last lesson video in this video, we're going to talk about how enzymes affect the activation energy of chemical reactions and, more specifically, how enzymes will lower the activation energy. And so, once again, enzymes catalyze chemical reactions by lowering their activation energy barrier or essentially lowering the transition state energy. Now reactions are going to occur much, much faster in the presence of an enzyme because the activation energy has been lowered. And remember the lower the activation energy. The faster the reaction, the higher the activation energy, the slower the reaction. And so let's take a look at our example down below to clear some of this up, looking at the reaction coordinate for enzymatic catalysis. And so, once again, we've got this graph where we got the free energy on the Y axis and the reaction progress on the X axis or the time as the reaction progresses. And so notice that we're showing an ex organic reaction because the reactions have higher energy than the products which have lower energy. And so notice that the activation energy eyes being represented in two different ways here in this image, and that's because we have two different curves. We have this blue curve that you can see right here and then we also have this red curve that you can see right here. And so the blue curve corresponds with the enzymatic reaction without an enzyme, and so you can see that the energy of activation without the enzyme is quite large. You can see that it's gonna be the difference in the energy between the reactant and the transition state for the blue curve, which is this large blue era that you see right here. This is again without an enzyme, so notice that the activation energy is large and that makes the reaction slow. But then notice that with the red curve right here, this represents the same exact chemical reaction except in the presence of an enzyme with an enzyme being present. And so notice that the red curve here has a much smaller activation energy. You can see it's shorter in comparison to the activation energy without an enzyme, and so because the activation energy is smaller, with an enzyme that makes the reaction occur much, much faster, and so you can see that the transition state here. For, uh, the reaction in the presence of an enzyme with an enzyme is much, much lower, and so that makes the activation energy lower. And that ends up making the reaction proceed faster in the presence of an enzyme. So, really, the main take away here of this video is that enzyme speed up chemical reactions by lowering the energy of activation. And so this here concludes our video, and we'll be able to get some practice applying these concepts as we move forward in our course, so I'll see you all in our next video.