Which of the following rate constants is negligible for the initial velocity (V 0 ) of an enzyme-catalyzed reaction?

So this practice problem asks, which of the following rate constants is negligible for initial velocity v naught of an enzyme catalyzed reaction? And we've got these 4 potential answer options below. Now, we know that k one is going to be the enzyme substrate association rate constant for essentially taking the free enzyme and the free substrate and associating them together to form the enzyme substrate complex. So this will be k 1. Now k minus 1 will be the reverse reaction of that. So essentially taking the enzyme substrate complex and dissociating it backwards to reform the free substrate and the free enzyme. So that will be k minus 1. And then we know that k 2 is going to be the enzyme substrate, complex dissociation rate constant forwards to form the enzyme and the product, and so this will be k 2 here. And we also know that at the initial stages of an enzyme catalyzed reaction, we only add enzyme and substrate, but we don't add any products. So the product concentration is essentially 0. And if the product concentration is 0, that means that there's no product available for the product to associate with the enzyme and that means that this reverse reaction going backwards is not going to be able to occur, so it's going to be negligible. So we can say that at the initial stages of the reaction, only k 2 is going to occur. And really, it's k minus 2 that will be negligible and, will be ignored at initial stages of an enzyme catalyzed reaction. And so we can say that d here is the correct answer, and that can concludes this practice problem. So 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
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6. Enzymes and Enzyme Kinetics13h 38m
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6. Enzymes and Enzyme Kinetics

Rate Constants and Rate Law

Biochemistry

6. Enzymes and Enzyme Kinetics

Rate Constants and Rate Law

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Multiple Choice

Which of the following rate constants is negligible for the initial velocity (V ₀) of an enzyme-catalyzed reaction?

k₁.

k_-1.

k₂.

k_-2.

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Verified step by step guidance

Understand the context of enzyme kinetics: Enzyme-catalyzed reactions are often described by the Michaelis-Menten model, which involves several rate constants.

Identify the rate constants involved: In a typical enzyme-catalyzed reaction, k1 is the rate constant for the formation of the enzyme-substrate complex, k-1 is the rate constant for the dissociation of the enzyme-substrate complex back to enzyme and substrate, and k2 is the rate constant for the conversion of the enzyme-substrate complex to product.

Consider the initial velocity (V0) of the reaction: At the initial stages of the reaction, the concentration of the product is negligible, and the reverse reaction (product converting back to enzyme-substrate complex) is not significant.

Determine which rate constant is negligible: Since the reverse reaction of the product formation (k-2) is not significant at the initial stages, k-2 is considered negligible for the initial velocity.

Conclude that k-2 does not affect the initial velocity: The initial velocity (V0) is primarily determined by k1, k-1, and k2, with k-2 being negligible because it involves the reverse reaction of product formation, which is not relevant at the start of the reaction.