enzymes

Introduction to Enzymes

  • Notice how enthusiasm for science leads to personal favorites in topics, like:

    • Favorite dinosaur

    • Favorite animal

    • Favorite flower

  • Unique favorites could include:

    • Favorite protist

    • Favorite amino acid

    • Favorite nitrogenous base

    • Favorite enzyme: ATP synthase is mentioned as a personal favorite.

  • Importance of learning about enzymes as they are vital to understanding biological processes.

Enzyme Examples in the Human Body

  • Enzymes are critical in various functions throughout the human body, especially in:

    • Digestion

    • Each enzyme has a specific role in breaking down biomolecules.

  • Four main biomolecules involved in digestion:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

Key Enzyme Examples:

  • Amylase

    • Enzyme that breaks down carbohydrates.

    • Location: Mouth

    • Function: Breaks the glycosidic linkages in starch (a large carbohydrate) into smaller carbohydrates.

  • Lipase

    • Enzyme that breaks down lipids.

    • Location: Small intestine

    • Function: Breaks the ester bonds in triglycerides (a type of lipid) into fatty acids and glycerol.

  • Pepsin

    • Enzyme that breaks down proteins.

    • Location: Stomach

    • Function: Breaks peptide bonds in proteins into peptides.

  • Trypsin

    • Another enzyme for protein breakdown.

    • Location: Small intestine.

  • Nucleases

    • Enzymes that break down nucleic acids (DNA and RNA).

    • Function: Break down phosphodiester bonds in DNA and RNA into nucleotides.

Additional Notes on Digestion:

  • After biomolecules are broken down into smaller pieces, other digestive enzymes can further process them.

  • Enzymes are found not just in humans, but in:

    • All living organisms (example: Venus flytrap)

    • Even some types of enzymes in viruses.

Cofactors and Coenzymes

  • Active Site

    • Region on the enzyme where the substrate binds to form an enzyme-substrate complex.

    • Induced fit: Enzyme changes shape slightly for a better fit when the substrate binds (metaphor: enzyme-substrate hug).

  • Enzymes often require cofactors and coenzymes to function:

    • Cofactors

    • Typically inorganic (e.g., zinc, iron).

    • May be permanent or temporary.

    • Coenzymes

    • Typically organic (e.g., many vitamins).

    • Also may be permanent or temporary.

  • Example: DNA polymerase, an enzyme involved in DNA replication, often has a zinc ion as a cofactor.

Enzyme Inhibition

  • Enzyme inhibitors can be reversible or irreversible:

    • Competitive Inhibitors

    • Bind to the active site, blocking substrate binding.

    • Substrates and inhibitors compete for the same binding site.

    • Noncompetitive Inhibitors

    • Bind to a different part of the enzyme (allosteric site).

    • Causes a conformational change that affects the active site's functionality even if the substrate is bound.

Role of Inhibitors in Biological Processes

  • Inhibitors can have both harmful and beneficial effects.

  • Example of harmful inhibitor: DDT

    • Acts as an inhibitor for certain enzymes, leading to health problems.

  • Feedback Inhibition: A regulatory mechanism where the product of a pathway inhibits an earlier step.

    • Hypothetical Example:

    • Enzyme 1 converts Substrate A to Intermediate B.

    • Enzyme 2 converts B to C.

    • Enzyme 3 converts C to final Product D.

    • If Product D is abundant, it may inhibit Enzyme 1, stopping the production to prevent waste.

    • This inhibition can be reversible, allowing the process to restart when needed.

Significance of Learning About Enzymes

  • Understanding enzymes is crucial for:

    • Comprehending essential biological processes.

    • Knowledge of medications that target enzymes in treating diseases and disorders.

  • Example: Treatment for high blood pressure with ACE inhibitors.

    • ACE inhibitors block angiotensin-converting enzymes, preventing the conversion of angiotensin to angiotensin II, which helps to lower blood pressure.

  • Another example: Penicillin

    • An antibiotic that inhibits the enzyme transpeptidase, preventing bacteria from constructing their cell walls.

Conclusion

  • Enzymes are ubiquitous and critical to various biological functions.

  • Continual exploration of enzymes is encouraged for deeper understanding of biological systems and medication impacts on health.