An enzyme reaction has an activation energy of 60 kJ/mol…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An enzyme reaction has an activation energy of . Take . Find the ratio of the rate constants when the temperature rises from to . Then take the enzyme at . The Arrhenius law alone would raise the rate relative to by a certain factor. But only of the enzyme is still folded at , and unfolded enzyme has no activity. Find the factor from the Arrhenius law, and the true activity at relative to .
Need a reminder? The key ideaShow
An enzyme lowers the activation energy . With the same frequency factor, with . Between two temperatures, . A denatured enzyme has lost its activity.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Use the two-temperature form of the Arrhenius law. Then multiply by the folded share.
Step 1. 300 K to 310 K. , so the ratio is .
Step 2. 310 K to 330 K. , so the factor is .
Step 3. Folded share. .
Answer: , and .
Check. The true activity at is only a third of the value at , although the temperature is higher. The enzyme has passed its optimum.
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