1.4.7 Limiting Factors Affecting Enzymes

Key Limiting Factors:

1. Temperature:

• As temperature increases, the rate of reaction increases up to the enzyme's optimum temperature due to increased kinetic energy and more frequent enzyme-substrate collisions.
• Above the optimum temperature, the rate declines as enzymes become denatured, losing their functional shape.

2. pH:

• Each enzyme has an optimum pH. Deviations from this pH can disrupt the bonds in the enzyme's tertiary structure, altering the active site and reducing activity.
• Extreme pH levels can lead to denaturation. For instance, pepsin works best in the acidic conditions of the stomach.

3. Enzyme Concentration:

• Increasing enzyme concentration increases the rate of reaction, as more active sites are available for substrates to bind.
• Beyond a certain point, the reaction rate plateaus as substrate concentration becomes the limiting factor.

4. Substrate Concentration:

• Increasing substrate concentration increases the rate of reaction as more enzyme-substrate complexes form.
• Once all active sites are occupied, increasing substrate concentration further will not increase the rate, as enzyme concentration becomes the limiting factor.

5. Inhibitors:

• Competitive Inhibitors: These inhibitors compete with the substrate for the enzyme's active site. As their concentration increases, the rate of reaction decreases, as active sites are temporarily blocked.
• Non-Competitive Inhibitors: These bind to a different site on the enzyme, causing a change in the enzyme's shape and active site. This reduces the reaction rate, as the substrate can no longer bind effectively.