Low activity doesn't mean little enzyme
- The idea
- Predict
- See it
- Why
- Check
The idea
“Low enzyme activity means the sample has only a little of that enzyme.”
More enzyme usually means more activity, so it's easy to treat them as one. A membrane, an inhibitor or the wrong conditions can hold enzyme back.
The short version
The mistake: Low enzyme activity means the sample has only a little of that enzyme.
What's actually true: Activity is how fast the enzyme works right now. The same amount reads low if substrate can't reach it or conditions slow it.
- Activity is a rate, how much product forms per minute. It depends on how much enzyme there is and whether substrate can reach it.
- An enzyme sealed in a lysosome shows little activity in a test tube, because substrate can't cross the membrane. That hidden activity is called latency.
- Temperature, pH, inhibitors and activators change how fast an enzyme works without changing how much is there.
- To compare amounts, open every membrane and measure under the same conditions. That activity tracks how much working enzyme is present.
On the exam: Before reading activity as amount, ask if substrate could reach the enzyme and if conditions matched.