An allosteric enzyme that follows the concerted model mechanism has a L 0 = 10,000 in the absence of substrate. A mutation in this enzyme caused the L 0 to now be 1/10,000 (reciprocal to its original value). What affect does this mutation have on the reaction rate of the enzymatic reaction?

So this practice problem says an allosteric enzyme that follows the concerted model mechanism has an allosteric constant or an l not equal to 10000 in the absence of substrate. A mutation in the same allosteric enzyme caused the allosteric constant l naught to now be 1 10 thousandth, which is really the reciprocal of its original value up above. So, the problem asks, what effect does this mutation have on the reaction rate of the enzymatic reaction? And we've got these 4 potential answer options below. Now, what we need to recall from our previous lesson videos is that the allosteric constant l naught is really just a ratio of the confirmations of the allosteric enzyme. And so recall the memory tool that helps us remember this ratio is laurin l naught, is tightroping over a relaxed crowd. And so, this, l naught ratio is really just the concentration of t states over the concentration of r states. And so looking at option a, it says that the enzyme will retain the t state and the reaction will not occur. Now, in the presence of this mutation, we know that the l naught is 1 10000th. And so that means, essentially, that there's a lot of R state and a small amount of T state in the presence of this mutation. And so, what this means is that, this mutation ultimately is not going to retain the t state. That would suggest that there would be a lot of t state, but we know that there's going to be a small amount of t state, with this mutation present. And so, for that reason, we can go ahead and cross off option a because the enzyme is not gonna retain the t state with this mutation. Instead, it's actually going to more so retain the r state. Now, moving on to option b, it says that the reaction rate remains independent of the substrate concentration. Now, we know that allosteric enzymes are going to display a sigmoidal curve, similar to this one right here. And so, of course, when it says that the reaction rate is independent of the substrate concentration, that means that by changing the substrate concentration, it will not affect the initial reaction velocity, but we know that that's not true. By changing the substrate concentration, we also change the initial reaction velocity. So again, we can cross off option b. So now we're between either option c or option d. And so taking a look at option d, it says that the kinetics will appear to be similar to Michaelis Menten kinetics since the enzyme is nearly always in the r state. And so, essentially, with, the mutation, again, there's going to be a much larger concentration of r state, than, the concentration of t state. And that means that the allosteric constant l naught is really going to be much smaller than 1. And when the allosteric constant is much smaller than 1, less than or equal to 1, essentially, Michaelis Menten kinetics are going to be displayed. And so ultimately, what we're saying is that the kinetics are going to appear to be similar to Michaelis Menten kinetics under this mutation. And so with the mutation, we would expect to see, a rectangular hyperbola on this curve some similar to this one. And so the black line represents the enzyme with the mutation, whereas the blue line represents, the enzyme with no mutation. And again, no mutation represents the original allosteric enzyme, which which is large. And, notice the larger the allosteric constant, the more sigmoidal the curve is. So we have a very sigmoidal curve here. And then, of course, as the allosteric constant gets smaller, so, less than or equal to 1 here, essentially, it's going to display Michaelis Menten kinetics. And so what we're saying is that it's true that option d is going to be correct. The kinetics are going to appear to be Michaelis Menten kinetics, since the enzyme is nearly always in the r state with this allosteric constant. So again, option d here is going to be the correct answer. And looking at option c, notice that it says something about the association constant k a, which we have not even yet talked about. Even though we are going to talk about it later in our course, we have not yet talked about it. And it turns out that this association constant is, ultimately going to change. So it says that it will not change with the mutation, but it turns out that it actually will. But, again, because we haven't yet talked about this, we could have ruled out this option as well. So, again, the correct answer for this problem is option d, and that concludes this practice. I'll see you guys in our next video.

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1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

7. Enzyme Inhibition and Regulation

Allosteric Enzyme Conformations

Biochemistry

7. Enzyme Inhibition and Regulation

Allosteric Enzyme Conformations

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Multiple Choice

An allosteric enzyme that follows the concerted model mechanism has a L ₀ = 10,000 in the absence of substrate. A mutation in this enzyme caused the L₀ to now be 1/10,000 (reciprocal to its original value). What affect does this mutation have on the reaction rate of the enzymatic reaction?

The enzyme will retain the T state and the reaction will not occur.

Reaction rate remains independent of the substrate concentration.

The association constant (Ka) for formation of the enzyme-substrate complex will not change with the mutation.

Kinetics will appear to be similar to Michaelis-Menten kinetics, since the enzyme is nearly always in its R state.

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Verified step by step guidance

Understand the concept of allosteric enzymes and the concerted model: Allosteric enzymes can exist in two states, T (tense) and R (relaxed). The concerted model suggests that all subunits of the enzyme are in the same state, either T or R.

Define L0: L0 is the equilibrium constant for the T to R state transition in the absence of substrate, calculated as [T0]/[R0]. A high L0 value indicates a preference for the T state.

Analyze the mutation effect: The mutation changes L0 from 10,000 to 1/10,000, indicating a shift in equilibrium towards the R state, as the R state is now more favored.

Relate the R state preference to enzyme kinetics: When the enzyme is predominantly in the R state, it is more active and binds substrate more readily, resembling Michaelis-Menten kinetics where the enzyme is mostly in the active form.

Conclude the effect on reaction rate: With the enzyme nearly always in the R state, the reaction rate will increase and become more dependent on substrate concentration, similar to Michaelis-Menten kinetics.