Enzymes Notes

Enzymes

• Almost all chemical reactions inside living things are controlled by enzymes.
• Enzymes are biological catalysts, speeding up reactions without being used up.
• Almost all enzymes are proteins.

Enzyme Action

• Enzymes speed up reactions without being used up.
• Substrates bind to the enzyme's active site, forming an enzyme-substrate complex.
• The enzyme converts substrates into products and releases them.

Enzyme Reactions

• Degradation: Breaking down a substrate.
• Synthesis: Building up products from substrates.

Enzyme Composition

• Enzymes are protein molecules made of amino acids.
• Most enzymes contain between 100 and 1,000 amino acids.
• The sequence of amino acids determines the enzyme's unique 3D structure.

Enzyme Specificity

• Enzymes are very specific about the reactions they catalyze.
• Only molecules with the right shape bind to the enzyme's active site.
• The active site has a specific shape.

Lock and Key Model

• A substrate fits into an enzyme’s active site like a key into a lock.

Denaturation

• Enzymes can be denatured by breaking bonds, changing their shape.
• Denaturation affects the shape of the active site, preventing it from working.

Factors Affecting Enzyme Activity

• Temperature: Enzymes have an optimum temperature.
• pH: Enzymes have an optimum pH.
• Substrate Concentration: affects the rate of reaction.

Optimum

• All enzymes work best at only one particular temperature and pH, called the optimum.

Temperature Effects

• Enzyme activity increases with temperature, up to its optimum.
• If the temperature is too high, the enzyme denatures and stops working.

pH Effects

• Enzymes work best at a specific pH.
• If the pH is wrong, the enzyme denatures.

Substrate Concentration

• Increasing substrate concentration increases the reaction rate up to a limit.
• Eventually, all active sites are occupied (saturated), and further increases have no effect.