The turnover number of an enzyme is the number of substrate molecules that one enzyme molecule can convert into products in one second when it is working at its maximum speed.
It shows how fast an enzyme can work.
For example:
- If an enzyme has a turnover number of 1000, it means one enzyme molecule can change 1000 substrate molecules into products every second.
Different enzymes have different turnover numbers.
- Catalase has a very high turnover number — it can act on millions of molecules each second.
- Lactase works slower and acts on fewer molecules per second.
In simple terms, the turnover number tells how quickly an enzyme performs its job.