For a particular chemical reaction, an inhibitor raises the KM but does not affect the Vmex . Th

For a particular chemical reaction, an inhibitor raises the...

For a particular chemical reaction, an inhibitor raises the $K_{\mathrm{M}}$ but does not affect the $V_{\text {mex }}$. This inhibitor a. is a competitive inhibitor. b. is a noncompetitive inhibitor. c. binds to the active site of the enzyme. d. binds to an allosteric site of the enzyme. e. is a competitive inhibitor and binds to the active site of the enzyme.

For a particular chemical reaction, an inhibitor raises the $K_{\mathrm{M}}$ but does not affect the $V_{\text {mex }}$. This inhibitor
a. is a competitive inhibitor.
b. is a noncompetitive inhibitor.
c. binds to the active site of the enzyme.
d. binds to an allosteric site of the enzyme.
e. is a competitive inhibitor and binds to the active site of the enzyme.

Key Concepts

Enzyme Active Site

The active site is the region on an enzyme where substrate molecules bind and undergo a chemical reaction. Competitive inhibitors typically bind to this site, impeding substrate access without affecting the enzyme's catalytic capacity at high substrate concentrations, thereby altering the kinetic parameter Km without changing Vmax.

Competitive Inhibition

Competitive inhibition occurs when an inhibitor resembles the substrate and competes for binding at the enzyme's active site. This leads to an apparent increase in Km, since a higher substrate concentration is required to achieve the same reaction rate, but Vmax remains unchanged because the inhibition can be overcome by increasing substrate levels.

Michaelis-Menten Kinetics

This concept describes the relationship between enzyme activity and substrate concentration, typically characterized by two parameters: Km (the substrate concentration at which the reaction rate is half of Vmax) and Vmax (the maximum reaction velocity). Changes in these parameters indicate different modes of enzyme modulation or inhibition, providing insight into how enzymes interact with inhibitors and substrates.

Transcript

00:01 Okay, this question addresses how an enzyme reacts when exposed to different kinds of inhibitors, particularly when it comes to things to do with the velocity of the reaction and the substrate concentration.

00:18 Now, in this case, we first have to address the concept of vmax.

00:23 What is vmax? vmax is the maximum velocity, the maximum velocity of that chemical reaction.

00:32 Rate.

00:33 So in this case, it would be, in this first case here, we will make this the vmax, and that would be this velocity here, noted by this blue line.

00:48 And i'm making the same kind of reaction happen in both graphs.

00:53 So this is also going to be the vmax, which is the maximum velocity of that reaction right here.

01:00 Now the other concept we're seeing here is the km.

01:04 So what's the km.

01:06 It's not velocity.

01:08 It is substrate concentration.

01:11 The substrate concentration at which the velocity is half of its maximum.

01:17 So in this first graph here, you see where the velocity is.

01:21 You go to the halfway point and that would be about half the velocity.

01:27 So you go across until you get to your reaction rate line and now you go down and that concentration would be your km.

01:41 So that's the same thing here, about halfway down from the velocity, go across, and down, and that's your km.

01:52 Okay, so now we are going to address the different kinds of inhibitors.

01:58 Now there's two main kinds of inhibitors.

02:00 One we call a competitive inhibitor and it's called competitive because it competes with the substrate.

02:09 What does it compete with the substrate for? well, it competes for where the substrate is going to attach to.

02:22 So that would be the active site.

02:32 That's why it's called competitive, because it's competing with the substrate for the active site...

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