Lecture on Enzymes

Introduction to Enzymes

• Enzymes are specialized globular proteins.
• They facilitate chemical reactions by either forming or breaking bonds.
• Enzymes have a specific structure known as the active site, essential for their function.
• Active sites bind specifically to one substrate, showcasing enzyme-substrate specificity.
• Enzyme names typically end in "-ase" (e.g., lactase breaks down lactose).

Structure and Function

• Active Site:
  • Contains a catalytic site (few amino acids in length).
  • Three-dimensional structure supports bond formation/breakage.
• Enzyme-Substrate Specificity:
  • Each enzyme binds to one substrate; specificity ensures proper reactions.
  • Induced fit model: both enzyme and substrate alter shape during bonding.

Enzymes as Catalysts

• Enzymes speed up reactions without changing the reaction's nature.
• Enzymes lower the required activation energy, facilitating faster reactions.
• They bring substrates together in optimal orientation to reduce energy barriers.

Energy Considerations in Reactions

• Activation Energy:
  • Energy required to achieve the transition state in a reaction.
  • Enzymes lower activation energy, making reactions more frequent and feasible.
• Energy in Chemical Reactions:
  • Enzymes assist in both exothermic and endothermic reactions.

Metabolism and Enzymes

• Metabolism: Sum of all chemical reactions in the body.
  • Enzymes are crucial for efficient metabolic reactions by lowering activation energy.
  • Enzyme-substrate specificity allows control over reaction timing.

Metabolic Pathways

• Anabolism:
  • Builds molecules by forming bonds between monomers (e.g., protein synthesis, photosynthesis).
  • Supported by enzyme-driven condensation reactions.
• Catabolism:
  • Breaks down molecules (e.g., digestion, cellular respiration).
  • Involves hydrolysis reactions to break bonds and release energy.

Factors Affecting Enzyme Activity

• Denaturation:
  • Changes in temperature or pH can alter enzyme structure, affecting function.
• Temperature:
  • Increases kinetic energy up to a point; too high can denature enzymes.
• pH:
  • Each enzyme has an optimal pH range.
  • Deviations can denature the enzyme, reducing activity.
• Substrate Concentration:
  • Increased substrates can increase reaction rates until enzymes are saturated.

Measuring Enzyme Activity

• Reaction Rates:
  • Calculated by measuring substrate conversion or product formation over time.
  • Understanding rate graphs is crucial for exams like IB.
• Experimental Design:
  • Identify independent, dependent, and controlled variables in enzyme experiments.

Conclusion

• Understanding enzyme function and factors affecting their activity is essential for comprehending biological processes.
• Enzymes' role in metabolism and their ability to act as catalysts make them vital for sustaining life processes.

Ensure familiarity with enzyme activity graphs and basic principles of enzyme kinetics for exams and practical applications.