Effect of Temperature
- Increasing temperature increase rate of reaction
- Particles move faster and are therefore more likely to collide
- Temperature coefficient,
Q10= how much the rate of reaction increases with a 10℃ rise. (usually doubles) - Optimum temperature is the temperature at which the rate of reaction is fastest
- Past optimum, the bonds holding the enzyme together vibrate, and eventually denature permanently.
Thermophiles
- Organisms adapted to living in very hot temperatures
- Enzymes are more stable and shapes are more resilient to change
- More disulphide bridges are present
Cold environments
- Some enzymes have more flexible structures, and are therefore less stable
- Small temperature changes will denature them
Effect of pH
- H⁺ ions decrease the pH
- Optimum pH is the level at which the rate of reaction is greatest
- H⁺ interacts with polar groups and charged R groups, causing bonds to break and substrate no longer fits into active site when pH is far from optimum
Substrate concentration and enzyme concentration
Substrate
-
As substrate concentration increases, the number of substrate molecules/atoms/ions in an area/volume increases
- The same is true for enzyme concentration
-
Increased chance of successful collisions
-
Vmax is the maximum rate of reaction
- It occurs when all active sites are occupied by substrate particles.
Enzyme
- Increasing enzyme concentration increases the number of active sites available
- This increases the number of enzyme-substrate complexes that can be formed, increasing the rate of reaction
- Vmax can be increased by increasing the substrate concentration and/or temperature