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7. Enzyme Inhibition and Regulation

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All right. So now that we've covered the degree of inhibition on the free enzyme in the enzyme substrate complex, Alfa and Alfa Prime, as well as the apparent K. M and the apparent V Max in this video, we're going to talk about the inhibition effects on reaction rate. And so way back in our previous lesson videos, we talked about two different equations that allowed us to calculate the initial reaction velocity or the V, not oven enzyme catalyzed reaction. And those two equations that we talked about work. The McHale is meant in equation and the line Weaver Burke equation. And so, if Alfa and Alfa prime our degree of innovation factors that quantify the effect that an inhibitor has on this initial reaction velocity, then that must mean that these two equations, the McHale is mentioned and the line we were burke equations must include the degree of inhibition factors specifically in the presence of inhibitors. And so, in our next lesson video, we're going to talk about how both Alfa and Alfa Prime can be included in the MK ill is meant in and the line with Robert equations, uh, depending on the type of inhibitor. And so I'll see you guys in that video there

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So from our last lesson video, we know that the McHale is meant in. And the line Weaver Burke equations are gonna change just a little bit in the presence of inhibitors because we know that Alfa and Alfa Prime are gonna be included into these equations in the presence of inhibitors. Now, from our previous lesson videos, we know that the inhibition constants K I and K Prime I are very, very, very similar to the McHale is constant K. M. And we know for sure that the McHale is constant. K m is definitely included in the McHale is meant an end line. We were burke equations, but it turns out that the inhibition constants K I and or K prime I can also be included into the McHale is meant in as well as the line Weaver Burke equations. And so this allows biochemist to measure the inhibitor effects on the initial reaction velocity or the V, not of an enzyme catalyzed reaction in the presence of inhibitors. Now, even though K I and K Prime I are definitely included in these equations in the presence of inhibitors, um, they're not directly included, and so they're actually going to be indirectly included via the degree of inhibition factors. And so, um, recall that the degree of inhibition factors are Alfa and Alfa pronto. And so recall from our previous lesson videos that Alfa and Alfa Prime can be defined using the inhibition Constance Kay I and K Prime I. And so even though when we look at our equations down below, we're not going to see Kay I and K Prime I. But when we see that Alfa and Alfa Prime are included, we know that they include K I and K Prime I indirectly. And so we covered this in our previous lesson videos. But it's important to emphasize here that depending on the type of inhibitor, Alfa and or Alfa Prime can impact the cam and or the V Max in different ways, and we'll be able to see that down below. But when it comes down to it in the presence of inhibitors, all we need to do is simply substitute the normal K M and V Max. That air present in the McHale is meant in equations with the apparent K M and the apparent V max from the appropriate inhibitor, and so we covered the different apparent cams and apparently maxes and our previous lesson videos. And so if you compare and contrast, you'll be able to see how these equations down below will change simply by substituting the K M and the V Max into these equations. And so there's ah lot of information here in, uh, this table. And so I definitely do not expect you guys to memorize all of these equations, um, in the presence of inhibitors right now. And actually, as we move forward in our course, we're going to revisit each of these equations, um, and our future videos for these different types of inhibitors. And so right now, all I really want you guys to take away from this video. Is that again, depending on the type of inhibitor the makayla meant in as well as the line we were Burke equations can change in different ways. And so all we need to do to figure out how they change is simply by substituting the K m, the apparent cam and the apparent V Max. And so this first row right here is specifically how competitive inhibitors affect the McHale is mentioned, and the line we were Burke equation. And so notice. Really, The only way that it changes is we substitute the K M with the apparent km for the competitive inhibitor. And then we just take the reciprocal of this equation and what we get is this equation here. Now, we could do the same for the next row here, which is specifically for uncompetitive inhibitors. And how uncompetitive inhibitors can alter the McHale is meant in equation in the presence of inhibitors. And so again, all we do is we substitute the V Max with the apparent V max, and we substitute the K m with the apparent K. M. And then all we need to do is take the reciprocal of this equation to get this equation over here and so down below. Uh, in this last road, what we have is how mixed as well as noncompetitive inhibitors affect. The McHale is mentioned in line Weaver Burke equations. And again, all we need to do is substitute the apparent V Max. Uh, here and then, of course, the apparent km here. And then if we want to get this equation, we just take the reciprocal of this equation here and so again, No need to memorize all of this. We're going to revisit everything that's here moving forward. But one of the main takeaways is that again, depending on the type of inhibitor the Mikhail's mentioned in line we were Burke equations will be different from one another, and they're different because the apparent cams and apparently maxes are different. And so this concludes our introduction to how these equations can be modified in the presence of inhibitors, and I'll see you guys in our next video.

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Problem

Select the option below that best fills in the blanks in order of their appearance in the following sentence:

In terms of the effects that the common types of reversible inhibitors can have on an enzyme’s kinetic variables such as K_{m} and V_{max}, notice that regardless of the type of inhibitor used, the ______ is always either unaltered or ______________, whereas the ______ can either be increased, decreased or remain unchanged depending on the type of inhibitor.

A

K_{m} ; increased ; V_{max}.

B

K_{m} ; decreased ; V_{max}.

C

V_{max} ; increased ; K_{m}.

D

V_{max} ; decreased ; K_{m}.

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