Lecture Notes: Enzymes and Their Importance

Introduction to Enzymes

• Enzymes are crucial biological molecules that act as catalysts in various biochemical reactions.
• Personal anecdote: The speaker's favorite enzyme is ATP synthase.
• Enzyme-related topics include enzyme examples, cofactors and coenzymes, inhibitors, and feedback inhibition.

Enzyme Examples in the Human Body

• Digestion:
  • Enzymes break down biomolecules: carbohydrates, lipids, proteins, nucleic acids.
  • Amylase: Breaks down carbohydrates in the mouth, targeting glycosidic linkages in starch.
  • Lipase: Breaks down lipids in the small intestine, targeting ester bonds in triglycerides.
  • Pepsin and Trypsin: Break down proteins. Pepsin acts in the stomach, trypsin in the small intestine, breaking peptide bonds.
  • Nucleases: Break down nucleic acids, targeting phosphodiester bonds, into nucleotides.
• Enzymes are involved in all human body systems, not just digestion (e.g., excretory, respiratory, circulatory systems).
• Enzymes are found in all living organisms, including plants and viruses.

Cofactors and Coenzymes

• Cofactors: Inorganic substances like zinc or iron.
• Coenzymes: Organic molecules, often vitamins.
• These assist enzymes in binding and often are essential for enzyme activity.
• Example: DNA polymerase uses zinc as a cofactor.

Enzyme Inhibitors

• Inhibitors: Can be reversible or irreversible.
  • Competitive Inhibitors: Bind to the active site, competing with the substrate.
  • Noncompetitive Inhibitors: Bind to an allosteric site, causing an enzyme shape change.
• Inhibitors can be harmful (e.g., DDT) or helpful (e.g., feedback inhibition).

Feedback Inhibition

• Biological process control mechanism.
• Hypothetical pathway: enzyme 1 converts A to B, enzyme 2 converts B to C, enzyme 3 converts C to D.
• Excess product D acts as a noncompetitive inhibitor for enzyme 1, stopping the process when enough product is made.

Importance of Understanding Enzymes

• Ubiquitous in biological processes and understanding their function is critical.
• Many medications act on enzymes, affecting health outcomes.
  • ACE Inhibitors: Lower blood pressure by inhibiting angiotensin-converting enzymes.
  • Penicillin: Inhibits transpeptidase, preventing bacterial cell wall formation.
• Medications can target enzymes in microbes that cause diseases.

Conclusion

• Enzymes are vital for life and understanding them can aid in treating diseases and disorders.
• Encouragement to remain curious about biological processes and enzyme functions.