Speeds up chemical reactions by having a groove on their surface called the active site
Substrate
The molecule that the enzyme reacts with, fits perfectly into the active site
Lock and key theory
The substrate must fit perfectly into the active site
Effect of temperature on enzyme activity
1. Gradually increase temperature
2. Measure enzyme activity (rate of reaction)
3. Activity increases as temperature increases
4. Reach optimum temperature
5. Activity rapidly decreases past optimum temperature
Optimum temperature
The temperature at which the enzyme is working at the fastest possible rate, maximum frequency of successful collisions between substrate and active site
Denaturation
At high temperatures, the enzyme molecule vibrates and the shape of the active site changes, so the substrate no longer fits perfectly
Effect of pH on enzyme activity
1. Alter pH
2. Measure enzyme activity (rate of reaction)
3. Activity is maximum at optimum pH
4. Activity drops to zero if pH is too acidic or too alkaline
