Enzyme Inhibition - Video Tutorials & Practice Problems

Enzyme Inhibition Concept 1

Now, when it comes to enzyme inhibition, we're going to say that inhibition itself decreases catalyze reaction rates. And we're gonna say that the inhibitor itself is a small molecule or ion that binds to the enzyme, it interferes with its activity. Now, the characteristics of inhibition, we could talk about it in terms of competitive versus noncompetitive and reversible versus irreversible. Now, in competitive inhibition, we're gonna say the inhibitor binds to the active site of the enzyme, it's gonna block that active site from the substrate. So it can't come in noncompetitive inhibition means that the inhibitor binds to a nonactives site. So like an allosteric site, and then we're gonna say reversible, well, reversible means that the enzyme can regain or enzyme regains its activity or can regain its activity. Irreversible means that we have a permanent loss of enzyme activity. So these are the different types of inhibitions that overall will hurt or decrease in enzymes effectiveness and activity.

Enzyme Inhibition Concept 2

So in this video, we're gonna take a look at the different types of inhibition, competitive versus noncompetitive, reversible versus irreversible. So if we take a look at the first one, we're gonna say we have reversible competitive inhibition here, we have our substrate and within the active side of our enzyme, we have the inhibitor in place. Now, here we're going to say that the inhibitor is similar in shape and size to the substrate. So it can take up the active site instead of the substrate. A great example of this Ibuprofen. Now, what's the interaction here? Well, here, this would be a non covalent interaction between the inhibitor and the enzyme at the active site. And what is the effect? Well, the effect we can see is that it's taking up that active site position. So it's blocking it from the substrate. And how would we reverse this effect? How could we get that inhibitor uh to not get in the way of our substrate while increasing the concentration of our substrate would help to lower the effect of this inhibitor. Now reversible noncompetitive here, we have our active site, we have our substrate and then down here we have our inhibitor, it attached somewhere else that is not the active site. So here we're gonna say that when it comes to the inhibitor, it does not resemble the substrate shape because it's not binding to the active site where the substrate would go. Great example of this are heavy metals. Now, here, this is also non covalent in terms of interaction. But now it's at the non active site. Here, we're gonna say it causes a shape change or in the enzyme and in the active site. But by the enz the inhibitor attaching itself to this part down here, which is not the active site, it's actually gonna cause a ch a shift or change in the shape of this active site, it changes shape. So the substrate can no longer attach effectively to the enzyme. Here, we're going to say how could we reverse this effect? Well, we'd have to use special types of agents. They would have to bind to the inhibitor so that they cannot bind to the nonactives site and change the active site of the enzyme. Finally, we have irreversible here, we have our substrate, we have our enzyme and the inhibitor has attached to the active site. Here, we would say that when it comes to the inhibitor, it, they do not resemble the substrate shape. In this case, we could talk about poisons and different types of venoms belonging to this type of inhibition. Now, here we're gonna say we have covalent in terms of its interaction with our group within the active sight. And we're gonna say here that the effect is it blocks the active site, the inhibitors attaching itself to that active site. And here the inhibition is permanent. So this can do some long lasting damage and effects in terms of ir irreversible inhibition. So we've talked about the different types of inhibition to remember, competitive versus noncompetitive, reversible versus irreversible.

Enzyme Inhibition Example 1

Here in this example question, it says match each type of inhibition with the correct statement. So A is reversible, competitive B is reversible noncompetitive and C is irreversible. The first one says inhibitor decreases enzyme activity by binding at sight other than the active site. Well, remember in our different types of inhibition that we covered, we'd say that the reversible noncompetitive is the only one that has the inhibitor binding to a site that is not the active site. So first, it's gonna be b next formation of strong covalent bond leads to permanent loss of enzyme activity. So remember when it comes to irreversible inhibition, it's the covalent of the R groups that are binding to the active site. Also, it says permanent. Remember the effect here is permanent when it comes to irreversible. So this would be c next substrate is unable to bond with active site due to change in enzyme structure. All right. So for this one, they're talking about the active site changing form. This happens when the inhibitor attaches to the nonactives site, it causes what we call a confirmational change in our active site. The shape changes. So the substrate can no longer effectively attach to it. This happens with reversible noncompetitive inhibition. Next, increasing concentration of substrate increases reaction rate. We said that the reversible competitive inhibition, its effects can be reversed. If we increase the amount of substrate, this is gonna put the inhibitor at a disadvantage where it won't be able to effectively bind to the active site. So here this would be A, so we'd say that the statements would be BC B and A for this particular example question.

Which of the following inhibitors could be a reversible competitive inhibitor for acetylcholinesterase if its substrate is acetylcholine?

• A.
• B.
• C.