Overview
This lecture explains how enzymes function as biological catalysts, their mechanisms, optimal conditions, and their practical uses in industry and daily life.
What Are Enzymes?
- Enzymes are proteins that speed up chemical reactions without being changed or used up.
- They are called biological catalysts because they lower activation energy, increasing reaction rates.
- Enzymes are reused after each reaction and remain unchanged.
How Enzymes Work
- Enzymes interact with specific substrates by binding at the active site.
- The enzyme-substrate complex forms through a lock and key mechanism, fitting only specific substrates.
- Once the reaction occurs, the enzyme releases the product and can catalyze further reactions.
- Enzymes can break down large molecules, build up larger ones from small units, or convert molecules from one form to another.
Factors Affecting Enzyme Activity
- Enzymes require optimal substrate concentration to maximize reaction rates.
- Excess product can decrease enzyme efficiency by limiting enzyme-substrate collisions.
- Each enzyme has optimal temperature and pH; rates increase with temperature up to a point before denaturation occurs.
- Enzymes that function in acidic environments, like the stomach, have a lower optimal pH.
Examples and Applications of Enzymes
- Protease breaks down proteins into amino acids.
- Carbohydrase converts carbohydrates into glucose.
- Lipase breaks down fats into fatty acids and glycerol.
- Catalase rapidly breaks down toxic hydrogen peroxide into water and oxygen.
- Enzymes are used in washing powders (to remove protein and fat stains) and in food industries (pectinase helps extract juice from fruits).
Key Terms & Definitions
- Enzyme — a protein that acts as a biological catalyst to speed up chemical reactions.
- Activation Energy — the minimum energy required for a reaction to occur.
- Substrate — the molecule upon which an enzyme acts.
- Active Site — the specific region of an enzyme where the substrate binds.
- Lock and Key Mechanism — model explaining how enzymes and substrates fit together precisely.
- Denaturation — the loss of an enzyme’s shape and function due to unsuitable temperature or pH.
Action Items / Next Steps
- Review the effects of temperature and pH on enzyme activity.
- Watch the upcoming video on enzyme denaturation.