The enzyme trypsin catalyzes the breakdown of many structurally diverse proteins in foods. Does the induced-fit or lock-and-key model explain the action of trypsin better? Explain.

Question

Accepted Answer

Hello everyone. And welcome back. Our next question says the enzyme carbonic anhydrase catalyzes the conversion of carbon dioxide and water into bicarbonate and a proton, which model better explains the action of carbonic anhydrase. A induced fit model. The enzyme's active site undergoes a confirmational change upon substrate binding allowing it to better accommodate and catalyze the reaction B lock and key model. The enzyme's active site has a rigid structure that perfectly fits the substrate facilitating the reaction without significant confirmational changes. C induced Fit model. The enzyme's active site remains rigid and does not change shape during substrate binding or D lock. And key model, the enzyme's active site is highly flexible and adapts significantly to the shape of the substrate. So even without knowing anything about carbonic anhydrase, we can rule out two of these descriptions as being an incorrect definition of the model. So choice C which is the induced fit model says the enzymes active site remains rigid, but that would be a description of the lock and key, which is fairly easy to remember. Since you think of how a key always fits a particular lock, the lock doesn't change shape. The two fit together perfectly and that specific key will always fit that specific lock and then choice d the lock and key model is incorrectly described as the enzymes active site is highly flexible and adapts significantly. So as we said, the lock and key model, the has the enzymes active site remaining rigid, the two aren't just directly switched because this definition here isn't even a correct definition of induced fit. Um The definition in choice A is a better one which says the enzymes active site undergoes a confirmational change because even in induced fit the enzymes active site and the substrate have similar shapes. So they resemble each other. But the enzyme undergoes a confirmational change when the substrate binds to it. As our choice A says, so which is a better model for carbonic anhydrase? Well, a hint here is that induced fit model is really thought to be a better model just in general for enzymes. So if you don't remember your enzyme or anything about it, choice A is definitely going to be the better bet and is indeed the correct answer here. So like most enzymes, carbonic anhydrase adopts an open configuration when there's no substrate. And this open configuration allows carbon dioxide to be able to enter the active site. Once carbon dioxide has settled into the active site and bound there forming the enzyme substrate complex. The enzyme then alters its configuration to a closed state sort of closing around the CO2 molecule which then allows the catalysis of the reaction to take place. So this change of structure that takes place means again that we're looking at this induced bit and recall that this means that the act of sight and the substrate have a shape that resemble each other, but they're not identical. Whereas the lock and key model posits that the active site of the enzyme and the substrate have identical shapes, they fit together like a lock and key and nothing changes in the enzyme site active site. Excuse me. So choice B lock and key model, this is a correct description of the lock and key model but is not the best explanation of the enzymatic action of carbonic anhydrase. So our best model for explaining the action of carbonic anhydrase is choice a the induced fit model. See you in the next video.

The enzyme trypsin catalyzes the breakdown of many structurally diverse proteins in foods. Does the induced-fit or lock-and-key model explain the action of trypsin better? Explain.

Verified video answer for a similar problem:

Key Concepts

Induced-Fit Model

Lock-and-Key Model

Enzyme Specificity