Enzymes and Their Functions

Enzyme Definition

• Biological catalysts
• Not consumed during a chemical reaction
• Essential for many biological processes
• Mostly proteins
• Highly specific, function optimally at body temperature (37°C) and physiological pH (7)
• Suffix "-ase"

Activation Energy

• The minimum energy required for a chemical reaction to start
• Catalysts reduce activation energy

Enzyme Classification

• Oxidoreductases
  • Catalyze oxidation-reduction reactions
• Transferases
  • Transfer functional groups
• Hydrolases
  • Break down molecules by adding water
• Lyases
  • Break down molecules, but don't require water
• Isomerases
  • Convert molecules into isomers
• Ligases
  • Join molecules together

Mechanism of Enzyme Action

• Binding of substrate to the enzyme's active site
• Active site is the specific area that binds to the substrate

Factors Affecting Enzyme Activity

Temperature

• Increases reaction rate, up to a point
• Beyond the optimal temperature, the enzyme denatures, and its activity decreases

pH

• Each enzyme has an optimal pH
• Deviation from the optimal pH can denature the enzyme

Enzyme Concentration

• Increased enzyme concentration leads to a higher reaction rate
• Up to a point where the substrate becomes limiting

Substrate Concentration

• Increased substrate concentration leads to a higher reaction rate
• Up to a point where the enzyme becomes saturated and the reaction rate plateaus