Lecture Notes: Enzymes

Importance of Enzymes

• Enzymes are crucial for life; they make many life processes possible.
• Most enzymes are proteins, although there are ribozymes and other non-protein enzymes.
• Enzymes often have names ending in "-ase."

Function of Enzymes

• Activation Energy: Enzymes lower the activation energy of reactions, making it easier for reactions to occur.

  • Speed: Enzymes can make chemical reactions occur up to a billion times faster.

• Biological Catalysts

  • Speed up reactions without being consumed or altering the end products.
  • Can perform up to 20,000 reactions per second without being altered.
  • Allow reactions to happen without harming homeostasis.

Specificity and Functionality

• Enzymes are highly specific; akin to a lock and key model.

  • Example: Sucrase breaks down sucrose, lactase breaks down lactose.

• Influencing Factors

  • pH and Temperature: Extreme changes can denature enzymes, halting metabolism and leading to life-threatening conditions.
  • Substrate Concentration: More substrate increases reaction rate until saturation.

Enzyme Types and Helpers

• Types of Enzymes

  • Enzymes can break down substrates (e.g., sucrose) or synthesize products from smaller reactants.

• Cofactors and Coenzymes

  • Many enzymes require cofactors (inorganic) or coenzymes (organic) to function.
  • Cofactors: Usually minerals, e.g., zinc for DNA polymerase.
  • Coenzymes: Typically vitamins, e.g., niacin for NAD, riboflavin for FADH2.
  • Terminology: Apoenzyme (protein portion) + cofactor/coenzyme = holoenzyme.

Conclusion

• Enzymes are essential for life and understanding their function is key to understanding biological processes.
• Their unique ability to speed up reactions without altering the body’s homeostasis makes them irreplaceable in biological systems.