What do we mean when we say an enzyme is saturated with substrate? When an enzyme is saturated with substrate, how does adding more (a) substrate and (b) enzyme affect the rate of the reaction?

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All right. Hello everyone. So this question is asking us what is the implication when we say that the enzyme is fully occupied by a substrate? How does adding more enzyme in substrate influence the rate of the chemical reaction? So here right, the enzyme is a catalyst. So when you have an enzyme reacting with its substrate, that substrate is converted into an end product. So when we talk about this reaction, it's also worth remembering that we have multiple enzymes and multiple equivalents of the substrate in our cell or in our solution. Right? So eventually we reach a point known as saturation. And when we talk about enzyme saturation, what we mean to say is that every enzyme that's in our environment in our solution has been occupied or has been bound with a substrate. So enzyme saturation means that we have all of our enzyme molecules binding to a substrate. This implies that the enzyme is working at maximum capacity and the reaction rate is at its maximum. So we also have the maximum reaction rate. So now let's talk about the other scenarios for that second part of the question. What happens first if the amount of the enzyme, the amount of the catalyst is increased or actually let's go ahead and talk about the substrate first. What happens if more substrate is added? But the concentration of the enzyme remains the same. Well, before this, the enzyme had reached maximum capacity, right, we have all of our enzyme molecules binding to a substrate already. So because of this increasing the concentration of the substrate is not going to change the reaction rate. Because if you're not increasing the concentration of the enzyme, then those additional molecules of substrate cannot react because the enzyme is already at maximum capacity. But what happens if you increase the concentration of substrate and you increase the concentration of the enzyme or the catalyst? Well, at that point, you are going to increase the reaction rate because those extra molecules of the substrate can bind with the added molecules of the enzyme. And so you're increasing the the rate at which the reaction proceeds even more because now you have more active sites available for binding and there you have it. So here on the screen, I'm going to scroll down. So you can see this final answer that I had prewritten earlier. So essentially, here's what happens when we talk about a fully occupied substrate. That means that all active sites of the enzyme are filled with reactant molecules. In other words, the substrate, adding more reactants causes no change in the rate of the reaction because you're not also increasing the concentration of the enzyme. However, adding more catalysts is going to increase the rate of the reaction because at that point, you've introduced more active sites for binding and there you have it. So with that being said, thank you so very much for watching. And I hope you found this helpful.

What do we mean when we say an enzyme is saturated with substrate? When an enzyme is saturated with substrate, how does adding more (a) substrate and (b) enzyme affect the rate of the reaction?

Verified video answer for a similar problem:

Key Concepts

Enzyme Saturation

Michaelis-Menten Kinetics

Reaction Rate