Enzymes and Their Functions

This page provides an overview of enzymes, their examples, and factors affecting their activity. It also explains enzyme-substrate interactions and their role in chemical reactions.

Examples of Enzymes

The page lists several important enzymes and their functions:

Example:

• Catalase: Breaks down hydrogen peroxide into water and oxygen
• Amylase: Secreted by salivary glands and pancreas to break down starch
• Trypsin: Secreted by the pancreas to break down proteins

Factors Affecting Enzyme Activity

The page discusses various factors that influence enzyme activity:

1. Temperature:
   • Increasing temperature generally increases reaction rate up to an optimum temperature
   • High temperatures can denature enzymes, changing the shape of the active site

Highlight: The factors affecting enzyme activity temperature include an optimal range and a point at which enzymes denature.

2. pH:
   • Enzyme activity increases with pH up to an optimum pH
   • Extremely acidic or alkaline conditions slow down enzyme activity

Vocabulary: Optimum pH refers to the pH level at which an enzyme functions most effectively.

3. Enzyme Concentration:

   • As enzyme concentration increases, the reaction rate increases (positive correlation)

4. Substrate Concentration:

   • Reaction rate increases with substrate concentration until a point of saturation
   • At saturation, all enzyme active sites are occupied

Definition: The point of saturation is reached when increasing substrate concentration no longer increases the reaction rate because all enzyme active sites are occupied.

Enzyme-Substrate Interactions

The page explains two models of enzyme-substrate interactions:

1. Lock and Key Model:
   • Represents how each substrate is specific to only one enzyme
   • The active site has a complementary shape to the substrate due to its tertiary structure

Example: The lock and key model enzyme substrate complex diagram shows how a specific substrate fits precisely into an enzyme's active site.

2. Induced Fit Model:
   • Demonstrates how the enzyme-substrate complex forms

Highlight: The induced fit model of enzyme action suggests that the enzyme's active site changes shape slightly to accommodate the substrate.

Energy and Enzyme Function

The page illustrates how enzymes lower the activation energy of reactions:

• Reactions without enzymes require more energy
• Enzymes reduce the activation energy needed for reactions to occur

Definition: Activation energy is the minimum energy required for a chemical reaction to occur.

This comprehensive overview of enzymes covers their types, factors affecting their activity, models of enzyme-substrate interactions, and their role in lowering activation energy, making it an excellent resource for OCR a level Biology enzymes studies.