What is meant by the term induced fit?

Video transcript

Hello, everyone. Here's our next question in which of the following models does substrate binding cause a confirmation all change in the enzyme. So we've got three models of enzymes along with our answer D. All of the above. And we want to look at for one that describes a situation where the binding of the substrate causes the confirmation the shape of the enzyme to change. So let's just um recall what each of these models of enzyme implies. So choice A. Is the lock and key model. Well, as we can imagine, lock and key involves describes the specific fit that the substrate fits into the shape of the active side of the enzyme, the way a key fits into a lock. So this accounts for the specificity of enzyme substrate binding. Um But that's it. It shows a sort of rigid shape. So this does not describe a change in the shape of the enzyme. Just shows a substrate binding and fitting like a key into a lock. So that would not be our correct answer here. To eliminate choice A. The induced fit model uh involves the substrate binding and then as a result of its binding, the binding causes a change in shape of the active site of the enzyme. So that is what we're looking for here. Where does substrate binding cause a confirmation of change? Which model describes that And that is induced fit. So induced means, you know, uh forced to happen or encouraged to happen. So that is can kind of help give us a clue um that the binding of the substrate induces a change in the enzyme. So we're gonna say Choice B. Is our answer. Um We no choice D has been eliminated because um we no choice A. Is incorrect. So let's just look at choice C. To make sure we've gone through everything. Choice C says transition state model. Well, the transition state model um says that when you have the chemical reaction, your substrate um being converted into your products that it goes through a transition state. And this model says that the transition state of the reaction or of the reactant, I should say, of the reactor binds more tightly to the active site than the original substrate. So this posits that the enzyme catalyzing the reaction because it encourages the conversion of the the reactant to that transitional state because the transition state binds more tightly fits more tightly to the active site. So that doesn't describe a substrate binding causing a change that describes a tight fit with the transition state. So, Choice C. Also not our answer. The correct answer is B. The induced fit model to describe substrate binding causing a confirmation all change. Hope we'll see you in the next video