A bacterial enzyme has the following temperature-dependent activity. (a) Is this enzyme more or

A bacterial enzyme has the following temperature-dependent...

Key Concepts

Thermal Denaturation

Thermal denaturation refers to the process by which an enzyme's structure is disrupted by excessive heat, leading to a loss of its functional three-dimensional conformation. This process reduces the enzyme's ability to catalyze reactions and is a critical consideration when evaluating enzyme activity at elevated temperatures, such as during a fever.

Optimal Temperature

Each enzyme has an optimal temperature at which its structure is ideally suited for catalysis, resulting in maximum activity. Deviations from this optimal temperature, either toward lower temperatures which slow down molecular motion or toward higher temperatures which can lead to denaturation, cause a decrease in enzyme activity.

Temperature Dependence of Enzymatic Activity

Enzymatic activity is highly temperature-dependent. As temperature rises, the kinetic energy of molecules increases, leading to more frequent collisions between enzyme and substrate, thus often increasing the reaction rate. However, if the temperature exceeds the optimum, the enzyme may begin to denature, resulting in a decline in activity.

Enzyme Kinetics

Enzyme kinetics is the study of the rates of enzyme-catalyzed reactions and how these rates vary with factors like substrate concentration and environmental conditions such as temperature. This concept is crucial for understanding how enzymes function differently at various temperatures, as reaction rates generally increase with temperature up to a certain point, after which the enzyme may lose activity.

Transcript

00:01 All right, we have a chart here showing us the activity of an enzyme, meaning how quick an enzyme is able to work or how efficient it is, given a range of temperatures in celsius.

00:13 So it looks like on this chart, our maximum is right at about 50 for our best activity.

00:19 What that means is that enzyme works the most efficiently at 50 degrees.

00:24 It's the most active.

00:26 It's the best.

00:27 So we're going to say that is 50 degrees.

00:30 All right.

00:30 Now if you go above that temperature, the activity slowly decreases as you go to the left, the same thing.

00:35 You start to decrease.

00:37 If you go outside of the range of the graph, right? so if you go down and to say this area below, i don't know, 18 degrees, something like that, what happens is the enzyme tends to freeze.

00:51 It doesn't denature.

00:53 It doesn't necessarily unfold.

00:55 Usually it just freezes in place, but it becomes an active.

00:59 So this is why things like yeast can be stored in the fridge.

01:04 This is why when we do biochemical research, we leave things in the fridge.

01:08 It tends not to break things as long as you don't go too cold, but it will slow everything down dramatically to a point where you're not worrying about the enzyme being active and doing things you don't want it to do.

01:20 Okay.

01:22 If you go above the range of the graph, okay, so a little past 80, you are now getting up into a high enough temperature that you will actually break or hurt the enzyme.

01:31 It'll start to denature, which means it's going to start to unfold.

01:35 And there is a point of no return for every enzyme that if you do take it past a certain temperature, it will not be able to fold itself back into place.

01:44 There's always a little bit of reversible range that you could get up maybe into the high 80s into the 90s.

01:50 And if you brought the temperature back down, it would fix itself.

01:53 It would be able to refold...

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